(cid:142)(cid:3) For percutaneous surgery involving nephroscopy further dilatation is achie ved with telescopic dilators, coaxial dilators or (most safely) with a balloon dilator, ove r which a 30 Ch sheath is advanced to maintain the tract. The balloon \200\224but not the g uidewire \200\224is removed. Nephrostomy tube drainage (cid:142)(cid:3) Usually, a pigtail nephrostomy catheter is advan ced over the guidewire to the appropriate position under fluoroscopy, and the guidewire is removed. The tube is secured within the collecting system by its \200\230pig- tail \200 \231 curl (which may have a strong \200\230memory \200\231 or a locking mechanism to preve nt unraveling) and at skin level. (cid:142)(cid:3) A similar technique is used for perinephric abscess or urinoma. PCNL (cid: 142)(cid:3) A large sheath is placed to maintain the tract. (cid:142)(cid:3) The rigid neph roscope is passed though the sheath alongside the guidewire. Saline is the usual irrigant. (cid:142)(cid:3) Stones or fragments less than 10mm in diameter can be grasped and removed. (cid:142)(cid:3) Larger stones are fragmented using ultrasonic, electrohydraulic, laser or pneumatic lithotripsy and removed piecemeal. The balloon catheter at the PUJ prevents fr agment migration during this procedure. (cid:142)(cid:3) All stone is removed \200\224sometimes via several tracts. Flexible nephro - scopy and fluoroscopy confirm stone clearance and exclude major collecting system injury. (cid:142)(cid:3) The ureteral balloon catheter is removed. (cid:142)(cid:3) A purpose-made double pigtail ureteral stent with attached coaxial large-bore nephrostomy catheter (Counci ll) is placed antegrade. (cid:142)(cid:3) Hemorrhage from the nephrostomy tract may be tamponaded with a Kaye balloon catheter. CHAPTER 13 Urology 550 Complications (cid:142)(cid:3) Hemorrhage, loss of renal parenchyma or kidney (cid:142)(cid :3) Perforation of the collecting system (cid:142)(cid:3) Loss of access to the collecting system (cid:142)(cid:3) Injury to adjacent structures \200\224bowel, pancreas, liver, splee n, major vessels (cid:142)(cid:3) Urosepsis (cid:142)(cid:3) Persistent obstruction and urinary fist ula. Follow-up (cid:142)(cid:3) Intensive monitoring in the immediate postoperative period (cid: 142)(cid:3) Urography after 24 \200\22348 hours to confirm stone-free status and urinary tract integrity (cid:142)(cid:3) Further procedures may be required including further nephroscopy or ESWL (cid:142)(cid:3) The nephrostomy tube and ureteral stent can be removed if imaging result is favorable and bleeding insignificant (cid:142)(cid:3) After a few hours observation, discharge for outpatient follow up in a fortnight. This page intentionally left blank CHAPTER 13 Urology 552 Extracorporeal shockwave lithotripsy (ESWL) Indications (cid:142)(cid:3) Small urinary trac t calculi (<2cm in the kidney, <1cm in the ureter), in the absence of obstruction or acute urinary tract infection. Note \200\224Hard stones may be difficult to fragment and the management of small lower pol e calyx calculi remains controversial. Position (cid:142)(cid:3) Depends on the stone position within the urinary tract and the ty pe of lithotripter (not all can accommodate a prone patient) (cid:142)(cid:3) Supine for renal and upper ureteral stones (cid:142)(cid:3) Prone for lowe r and midureteral stones and bladder stones (cid:142)(cid:3) Ensure excellent contact betwe en the patient \200\231s skin and the shockwave transmitting device. Preparation (cid:142)(cid:3) Confirm appropriateness of procedure and exclude (relative or abso- lute) contraindications (cid:142)(cid:3) Pregnancy (cid:142)(cid:3) Abdominal aortic aneury sm (cid:142)(cid:3) Bleeding diathesis or anticoagulation (cid:142)(cid:3) Urinary tract in fection or obstruction (cid:142)(cid:3) Antibiotics may be given orally preoperatively (cid :142)(cid:3) For non-opaque calculi, urinary tract opacification may be achieved by intravenous or retrograde pyelography (cid:142)(cid:3) Stone localization may be achieved using biplanar fluoroscopy and/or ultrasonography (cid:142)(cid:3) The need for sedation and analgesia or anesthesia depends on the patient and the type of lithotripter to be used. Procedure (cid:142)(cid:3) Position the patient so that the calculus is at the focal point of the shock wave (cid:142)(cid:3) Commence treatment at low power if the patient is awake (cid:142)(cid:3) R epeat imaging at intervals to confirm that the stone is still within the focal point, and to monitor fragmentation. Complications (cid:142)(cid:3) Failure to fragment calculus, or clear fragments (cid:142)(c id:3) Uro sepsis (cid:142)(cid:3) Steinstrasse \200\224a logjam of fragments, usually near the vesicoureteral junction or PUJ (cid:142)(cid:3) Haematoma, haematuria (cid:142)(cid:3) Significant injury to adjacent stru ctures (growth-plates in children, lung, bowel, panceas, liver, spleen, uterus, ovaries) \200\224fortunately very rare. This page intentionally left blank CHAPTER 13 Urology 554 Ureterorenoscopic procedures Indications Diagnostic (cid:142)(cid:3) Ureterorenoscopy (usin g rigid or flexible instrument) (cid:142)(cid:3) Urothelial biopsy Therapeutic (cid:142)(ci d:3) Removal or fragmentation of upper tract urinary calculi (cid:142)(cid:3) Resection or destruction of upper urinary tract urothelial neoplasms (cid:142)(cid:3) Treatment of obstr uctive lesions (congenital or acquired) of (cid:142)(cid:3) Calyceal infundibulum (cid:142)(cid:3) Ureteropelvic junction (cid:142)(ci d:3) Ureter. Position Dorsal lithotomy. Preparation (cid:142)(cid:3) If endopyelotomy is contemplated imaging of the related vascul ar anatomy is prudent (cid:142)(cid:3) Appropriate counseling and consent (cid:142)(cid:3) Arrange intraoperative fluoroscopy (cid:142)(cid:3) Treat UTI (cid:142)(cid:3) Antibiotics with anesthetic induct ion (cid:142)(cid:3) Prepare perineum and genitalia with antiseptic solution, perform EUA, and drape. Procedure (cid:142)(cid:3) Perform rigid cystoscopy, and, if appropriate, retrograde pyelog raphy. (cid:142)(cid:3) Pass a guidewire into the ureter. (cid:142)(cid:3) Dilatation of th e ureteral orifice and intramural ureter \200\224if necessary \200\224 may be done most safely using a balloon dilator. (cid:142)(cid:3) A ureteral access sheath may be helpful, especially for flexible ureteroscopic procedures, and is placed, using the Seldinger technique over a tapered dilat or and guidewire. The dilator is then removed. (cid:142)(cid:3) Pass the ureteroscope eithe r over the guidewire, or alongside it, under direct endoscopic vision with fluoroscopic control. (cid:142)(cid:3) Choose the device most appropriate for the job and pass it along the working channel of the ureteroscope. (cid:142)(cid:3) Visibility is achieved by irrigating through the ureteroscope. Irrigant flow is improved by intermittent pressure provided by a blood pump or manually using a syri nge or other device. (cid:142)(cid:3) Small calculi can be retrieved using a variety of graspers or wire baskets. (cid:142)(cid:3) Larger calculi (>5mm) are fragmented using one of the following: (cid:142)(cid:3) Electrohydraulic, laser (pulsed-dye or holmium YAG), ultrasonic or ballistic (Swiss lithoclast) lithotripsy. (cid:142)(cid:3) The first two can be used with flexible or rigid instruments, the last two with rigid instruments only. URETERORENOSCOPIC PROCEDURES1 555 (cid:142)(cid:3) Biopsies can be taken using cold forceps. (cid:142)(cid:3) Tumor can be va porized using the holmium YAG laser or resected using a ureteroscopic resectoscope. (cid:142)(cid:3) Strictures can be dilated using balloon dilators, or incised either under endoscopic vision using cold knife, electrosurgical knife, laser, or the Accucise device. (cid:142)(cid:3) It is not necessary to place ureteral stents after endoureteral proce- dur es without ureteral trauma or dilatation, but they should be used when there has been traum atic manipulation or extravasation. For endopyelotomy, special endopyelotomy stents are use d. Complications (cid:142)(cid:3) Ureteral avulsion (cid:142)(cid:3) Urinary extravasation, ur inoma (cid:142)(cid:3) Hemorrhage, \200\230clot colic \200\231 (cid:142)(cid:3) Injury to adjacent structures (iliac vessels, duodenum) (cid:142)(cid:3) Infection (cid:142)(cid:3) S tricture. Follow-up (cid:142)(cid:3) Urolithiasis (cid:142)(cid:3) Remove stents after a few days (cid:142)(cid:3) Endoureterotomy, endopyelo tomy (cid:142)(cid:3) Remove stents after 6 weeks (cid:142)(cid:3) Thereafter as for pyelop lasty (cid:142)(cid:3) Urothelial neoplasms (cid:142)(cid:3) Confirm disease-free status or plan definitive treatment (cid:142)(cid:3) Strict surveillance protocols are used, similar to those for bladder cancer, and involving imaging, urine cytology, and endoscopy. CHAPTER 13 Urology 556 Laparoscopic urology: introduction (cid:142)(cid:3) Laparoscopic surgery is one of the most rapidly progressive areas of urology. (cid:142)(cid:3) There is increasing evidence that surgical outcome is at least as good whe n certain major procedures are performed laparoscopically rather than using conventional sc alpel surgery. (cid:142)(cid:3) Evidence supports the following procedures being performed laparoscopically: (cid:142)(cid:3) Orchidectomy for intra-abdominal testes (cid:142)(cid:3) Ureterolithotomy (cid:142)(cid:3) Pyeloplasty (cid:142)(cid:3) Simple nephrectomy (cid:142 )(cid:3) Radical nephrectomy (cid:142)(cid:3) Nephroureterectomy (cid:142)(cid:3) Adrenalec tomy (cid:142)(cid:3) Renal cyst decortication. (cid:142)(cid:3) Currently, laparoscopic radical prostatectomy and live donor nephrec- tomy are also becoming established but long term results are awaited. (cid:142)(cid:3) Recent reports of major reconstructive procedures such as entero- cystoplasty and ileal conduit urinary diversion have been described in the literature. (cid:142)(cid:3) Benefits of laparoscopic surgery include: (cid:142)(cid:3) Shorter hospital stay (cid:142)(cid:3) Less analgesia required (cid:142)(c id:3) Fewer complications (cid:142)(cid:3) Quicker return to functional normality. Performing laparoscopic operations (cid:142)(cid:3) Careful patient selection is essential such as the consideration of exist- ing respiratory disease, obesity, organomegaly, coagula tion problems or previous surgery that may make laparoscopic procedures unneces- sarily dif ficult. (cid:142)(cid:3) Pneumoperitoneum can be achieved either by open (Hassan) or closed (Veress) techniques. (cid:142)(cid:3) CO2 is the most commonly used insufflant due to its inertness and solubility in blood. (cid:142)(cid:3) The intra-abdominal CO2 pressure is generally kept at around 15mmHg. (cid:142)(cid:3) Trocar placement depends on the procedure being performed. (cid:142)(cid:3 ) Transperitoneal or retroperitoneal approaches are commonly used. (cid:142)(cid:3) Trocars vary from 3 \200\22320mm in diameter and can be disposable or non-disposable. (cid:142)(cid:3) Trocar sheaths can accommodate many instruments including: (cid:142)(cid:3) Laparoscope (cid:142)(cid:3) Graspers (cid:142)(cid:3) Dissectors (cid:142 )(cid:3) Scissors (cid:142)(cid:3) Scalpel (cid:142)(cid:3) Electrocautery LAPAROSCOPIC UROLOGY: INTRODUCTION1 557 (cid:142)(cid:3) Retractors (cid:142)(cid:3) Suction (cid:142)(cid:3) Needle holders (cid:1 42)(cid:3) Suturing devices. (cid:142)(cid:3) Instruments also exist for specimen extraction, and often removal is achieved manually using a Pfannenstiel incision. (cid:142)(cid:3) Port-site closure is usually in layers with a subcuticular suture to skin. CHAPTER 13 Urology 558 Laparoscopic radical nephrectomy Indications (cid:142)(cid:3) Malignant tumors of the kidne y (cid:142)(cid:3) Renal vein or IVC involvement necessitates open surgery (cid:142)(cid:3) Large, polar tumors may be better served with conventional open surgery. Position Modified flank position with table break at the umbilicus. Incision Ports are umbilical, lateral (edge of the rectus sheath) and upper midline. Procedure (principles) (cid:142)(cid:3) The colon is reflected and on the right the duodenu m is Kocherised (cid:142)(cid:3) The ureter is identified and dissected (cid:142)(cid:3) Th e renal lower pole is mobilized (cid:142)(cid:3) Hilar dissection and vessel ligation is pe rformed (cid:142)(cid:3) The upper pole is mobilized (cid:142)(cid:3) The specimen is extra cted (it may be morcellated first). This page intentionally left blank CHAPTER 13 Urology 560 Laparoscopic pyeloplasty Indications (cid:142)(cid:3) Pelviureteric junction obstruction. ( cid:142)(cid:3) Long-segment obstruction or associated calculi may contra-indicate laparoscopic surgery. Position (cid:142)(cid:3) Initially, cystoscopy and retrograde pyelography are performed, a nd a ureteral stent is inserted with the patient in dorsal lithotomy position. (cid:142)(cid:3) Modified flank position is used for laparoscopic procedure. Incision (cid:142)(cid:3) For a retroperitoneal approach, a subcostal port is primarily sit ed beneath the tip of the 12th rib with secondary ports anterior (above the iliac crest in the anterior axillary line) and posterior (at the lateral border of paravertebral muscles). (cid:142)(cid:3) Ports for transperitoneal approach have been described above. Procedure (principles) (cid:142)(cid:3) The procedure is usually performed retroperitoneall y. (cid:142)(cid:3) Ureteral identification and proximal dissection is fundamental whichever approach is used. (cid:142)(cid:3) The renal pelvis and upper ureter are fully mobilized. (cid:142)(cid:3) Di smembered procedures such as the Anderson \200\223Hynes procedure (pp550 \200\2231) are most commonly performed but other procedures such as the Foley V-Y pl asty have been reported. (cid:142)(cid:3) The renal pelvis is transected circumferentially and excess pelvis removed. (cid:142)(cid:3) The proximal ureter is spatulated and anastomosed to the cut edge of the renal pelvis. (cid:142)(cid:3) Renal pelvis above the anastomosis is closed with a running suture. (cid:1 42)(cid:3) A drain is often placed as the repair is seldom watertight. This page intentionally left blank CHAPTER 13 Urology 562 Laparoscopic retropubic radical prostatectomy Indications (cid:142)(cid:3) Clinically local ized prostate cancer. (cid:142)(cid:3) Prior open prostate surgery is an absolute contra-in dication and previ- ous TURP may make laparoscopic radical prostatectomy impossible. Position Supine with lower limbs in lithotomy. Incision Five ports are placed in an upward-pointing chevron with the apex at the umbilicus . Procedure (principles) (cid:142)(cid:3) The retropubic space is explored and the vasa defer entia are identified and divided (cid:142)(cid:3) The seminal vesicles are mobilized and the prostate dissected off the rectum. (cid:142)(cid:3) Anterior perivesical dissection, with division of the urachus, allows incision of the endopelvic fascia. (cid:142)(cid:3) The dorsal venous complex is suture-ligated. (cid:142)(cid:3) The bladder neck is opened starting anteriorly and the seminal vesicles are seen when bladder neck and prostate are separated posteriorly. (cid:142)(cid:3) Prostatic vascular pedicles are divided. (cid:142)(cid:3) Attempts are mad e to preserve the postero-lateral neurovascular bundles. (cid:142)(cid:3) Finally the urethra is divided at the junction with the prostate (cid:142) (cid:3) The urethrovesical anastomosis is performed and the specimen removed. This page intentionally left blank CHAPTER 13 Urology 564 Laparoscopy for cryptorchidism (cid:142)(cid:3) Diagnostic laparoscopy is often necessary f or location of an undescended testis. (cid:142)(cid:3) Prior to laparoscopy confirmatory re-examination under anesthesia should be performed. (cid:142)(cid:3) An umbilical and two lateral ports are used to allow all of the abdomen to be examined. (cid:142)(cid:3) Atrophic testes can be removed, but normal-looking testes are identified can be placed in the scrotum by a variety of procedures. This page intentionally left blank CHAPTER 13 Urology 566 Complications of laparoscopic urology Failure to obtain pneumoperitoneum (cid:142)(cid:3) E quipment failure (cid:142)(cid:3) Pre-peritoneal placement of trocar (cid:142)(cid:3) Leaka ge of insufflant around trocar (especially with open placement) (cid:142)(cid:3) Bowel insu fflation (cid:142)(cid:3) Air embolism from blood vessel insufflation. Bowel injury (cid:142)(cid:3) During primary port placement (cid:142)(cid:3) Subsequently, including entrapment of intestine on exiting the abdomen. Vessel injury (cid:142)(cid:3) Abdominal wall vessel injury \200\224usually inferior epigas tric vessels (cid:142)(cid:3) Major vessels such as aorta or iliac arteries are infrequentl y injured Diathermy injuries Can be occult so vigilance is necessary. Urinary tract injury Bladder and ureteral injuries. Bleeding Can be from the sheath site or direct vessel injury. Acute hydrocele Due to accumulation of irrigant in the context of a patent processus vagina lis. Cardiac arrhythmias Hypothermia The insufflant used is generally not warmed so prolonged pr ocedures may result in decreased core temperature. Postoperative complications (cid:142)(cid:3) Subcutaneous emphysema (cid:142)(cid:3) Thromb o-embolic complications (cid:142)(cid:3) Postoperative chest, wound or urinary tract infect ion (cid:142)(cid:3) Wound complications such as incisional hernia at port sites. Chapter 14 567 14 Pediatric surgery P. Raine and G. Walker Surgery on the newborn 568 Anatomy of the child 570 Fluid and electr olyte management 572 Vascular access 574 Oesophageal atresia 576 Intestinal atresia 578 Gas troschisis 582 Exomphalos (omphalocele) 584 Meconium ileus 586 Hirschsprung \200\231s disea se 588 Necrotising enterocolitis 590 Sacrococcygeal teratoma 592 Congenital diaphragmatic h ernia (CDH) 594 Spina bifida 596 Release of tongue tie 598 Ranula 600 Preauricular skin tag and sinus 602 Branchial cyst/sinus 604 Thyroglossal cyst and fistula 606 Lymphangioma/cyst ic hygroma of neck 608 Dermoid cysts 610 Pyloric stenosis 612 Intussusception 614 Meckel \200\231s diverticulum 616 Acute appendicitis 618 Malrotation and volvulus 620 Epigastric h ernia 622 Umbilical hernia 624 Inguinal herniotomy 626 Hydrocele 628 Orchidopexy 630 Circum cision 632 Retraction of foreskin (adhesionolysis) 634 Prepuceplasty 636 Torsion of testis or appendix 638 CHAPTER 14 Pediatric surgery 568 Surgery on the newborn Newborns may need surgery for an antenatally or perinatally diagnose d congenital anomaly (e.g. duodenal atresia, multicystic kidney) or an ac- quired problem ( e.g. necrotising enterocolitis, testicular torsion). What- ever the underlying diagnosis, c ommon principles apply to pre-, peri- and postoperative assessment and management. A series of investigations and monitoring/supportive procedures may be indicated. Admission procedure (cid:142)(cid:3) Full history (cid:142)(cid:3) Maternal \200\224age, previous/intercurrent illness, drugs (cid:142)(cid:3 ) Obstetric \200\224parity, previous pregnancies (cid:142)(cid:3) Pregnancy/delivery \200 \224complications, mode of delivery, gestation (cid:142)(cid:3) Examination (cid:142)(cid:3) Full clinical examination (head to toe) (cid:142)(cid:3) Weight, length, h ead circumference \200\224plotted on growth chart (cid:142)(cid:3) Consent (cid:142)(cid:3) Informed consent from both parents for principle operation and secondary procedures (e.g. central venous long line) Investigations Necessary to establish baseline normality and for ongoing management: (cid:1 42)(cid:3) Blood tests performed on venous or capillary (heel-prick) specimens (cid:142)(cid:3) Full blood count (cid:142)(cid:3) Serum urea and electrolytes, liver funct ion tests, glucose, C-reactive protein (cid:142)(cid:3) Blood gas analysis (arterial or capillary): pO2, pCO2, pH, base deficit clotting screen (cid:142)(cid:3) Blood culture \200\224if any suggestion of infection. (cid:142)(cid:3) Radiology: chest and abdomen (both on one \200\230babygram \200\231 movie ). Vascular access Choice depends on likely duration/volume of infusion and on type of intrave nous fluid. (cid:142)(cid:3) Peripheral venous access via cannula in dorsum of hand, antecu bital fossa, dorsum of foot or scalp vein. (cid:142)(cid:3) Central venous access via peripherally inserted central line (epicath) \200\224 forearm/lower leg. (cid:142)(cid:3) Formal jugular vein (external or internal) cutdown and tunneled catheter from anterior chest wall. (cid:142)(cid:3) Arterial line (radial) if intravascular blood pressure monitoring and arterial blood gasses needed. Fluid and electrolyte requirements Fluid requirements for the newborn take account of: (cid :142)(cid:3) High glomerular filtration rate and physiological diuresis (cid:142)(cid:3) La rge surface area/body weight ratio and high insensitive losses (cid:142)(cid:3) High total body water (up to 75%) (cid:142)(cid:3) Blood volume 80 to 100ml/kg depending on maturity o r prematurity. SURGERY ON THE NEWBORN1 569 Water requirements range from: (cid:142)(cid:3) 100mls/kg on day 1 to 175ml/kg on day 7 for a very premature baby (birth weight <1250gm); (cid:142)(cid:3) 60mls/kg on day 1 to 150ml/kg on day 7 for a mature baby (>3000gm). Electr olyte requirements are approximately 2 \200\2234mmol/kg/day of sodium and chloride, 2mmol/k g of potassium, 1 \200\2232mmol/kg/day of calcium and phosphate, and 0.5mmol/kg of magnesiu m. The most suitable fluid for normal maintenance is usually 0.225% so- dium chloride with 10% dextrose. Acid/base balance Acid/base balance (normal pH and bicarbonate) is essential for normal met abolic and respiratory function. The commonest and most significant derangement (metabolic acidosis) should be corrected before submitting a neonate to anesthesia and surgery using t he formula: 8.4% NaHCO3 solution (ml) = weight (kg) \227 base deficit \227 0.3 Initially use half amount then repeat after rechecking gasses. Nutritional requirements A newborn cannot withstand any period of calorie starvation withou t detri- ment to healing and growth. Gut feeding is usually started with continuous low vol ume administration via a nasogastric tube. Unless enteral feeding can be started within 24 hours of surgery, intravenous nutrition will be needed. is achieved with >75kcal/kg/day and 100kcal/kg/day is the normal requirement. A balanced in take of carbohy- drate, lipid, protein (amino acids), vitamins and trace elements is needed in addition to water and electrolytes. Positive nitrogen balance Blood and blood products It is often advisable to group and save a baby \200\231s blood at initial venesec- tion so that a cross-match can be done rapidly if needed. (cid:142)(cid:3) Blood products \200\224fresh frozen plasma, cryoprecipitate and platelets \200\224 may be needed to counteract problems of coagulation disorder and disseminated intravascular coagul ation caused by sepsis. (cid:142)(cid:3) Red blood cell replacement is normally made using packed red blood cells on the basis of a circulating blood volume of between 80 \200\223100mls/kg. (cid:142)(cid:3) Excess circulating volume and cardiac overload is managed by frusemide infusion (1mg/kg) and hypoglycaemia may need to be cor- rected by a break in bloo d transfusion for dextrose administration. Antibiotic prophylaxis The argument for prophylactic antibiotic use in clean, non-contamina ted surgery is stronger for neonates because of decreased immunity. When- ever possible, th e policy should be guided by bacteriological cultures but \200\230best guess \200\231 anti biotics are: (cid:142)(cid:3) Cefotaxime/metronidazole for enteric organisms (gentamicin/ amoxycillin/metronidazole if more complex) (cid:142)(cid:3) Flucloxacillin for staphylococci (vancomycin for multiple resistance MRSA and coagulase-negative staphylococci). (cid:142)(cid:3) Antifungals should be considered after prolonged antibiotic use and in additionally compromised patients (cardiac defects, urinary obstruction). CHAPTER 14 Pediatric surgery 570 Anatomy of the child The surgeon should recognize the essential differences between the ana tomy of the child and that of the adult and be aware of the impor- tance of allowance for b ody weight and surface area. Weight Most calculations in pediatrics are dependent on knowing the weight of the child. In the emergency situation where the weight is not known, an estimated weight can be derived from the following equation (in children between 1 and 10 years): Weight (kg) = (age + 4) (cid:215) 2 In children and infants weight should be plotted on a centile chart. In older children this can be correlated to height, and in infants to length and head circumference. Surface area The proportions of the head, body, and limbs vary throughout childhood. Head a nd body are proportionately greater in relation to limbs than in adults. To establish body surface area, a specialized chart should be used which will take into account the age of th e child (Lund and Bowder). Abdomen The abdomen in the child is as broad as it is long, and is more square than rectang ular as in adults. This partly explains the preference for transverse incisions for abdomin al access. Small bowel In neonates the total length of small bowel is approximately 6(cid:215) crown- rump length. This equates to around 150cm in a term neonate. Large bowel The caecal pole is often higher in children so appendicectomy incisions should not be placed too low. The rectum should be the most disten- sible part of the large bowel, and if this is not the case on contrast en- ema, it raises the question of Hirschsprung \200\231s Disease. Anus In most infants, the anus should be of sufficient caliber to allow the pas- sage of th e examiner \200\231s little finger. The position of the anus in girls should be between one half and one third of the distance from the posterior fourchette to the coccyx. If it is c loser to the vagina, consider an anteri- orly placed ectopic anus. This page intentionally left blank