Irreversible ischemic renal failure caused by acute cortical necrosis is rare now in obstetrics (F rimat, 2016). Before widespread availability of dialysis, it complicated a fourth of obstetrical renal failure cases (Griinfeld, 1987; Turney, 1989). Most cases followed placental abruption, preeclampsia-eclampsia, and endotoxin-induced shock. Once common with septic abortion, this is a rare cause in this country today (Lim, 2011; Srinil, 2011). Histologically, the lesion appears to result from thrombosis of segments of the renal vascular system. he lesions may be focal, patchy, conluent, or gross. Clinically, renal cortical necrosis follows the course of AKI, and its diferentiation from acute tubular necrosis is not possible during the early phase. he prognosis depends on the extent of the necrosis. Recovery of function is variable, and stable renal insuiciency may result (Lindheimer, 2007a).
Rarely, bilateral ureteral compression by a very large pregnant uterus is greatly exaggerated. Resultant ureteral obstruction in turn may cause severe oliguria and azotemia. An extreme example is shown in Figure 53-6. In their series of 13 obstruction cases, Brandes and Fritsche (1991) described one woman with twins who developed anuria and a serum creatinine level of 12.2 mg/dL at 34 weeks' gestation. After amniotomy, urine flow resumed at 500 mL/hr, and her serum creatinine levels rapidly dropped to normal range. Eckford and Gingell (1991) described 10 women in whom ureteral obstruction was relieved by stenting. he stents were left in place for a mean of 15.5 weeks and removed 4 to 6 weeks postpartum. Others have reported similar experiences (Sadan, 1994; Satin, 1993).
FIGURE 53-6 A.Magnetic resonance image in a coronal plane of a pregnant woman with unilateral hydronephrosis caused by ureteral obstruction. The serum creatinine level was 8 mg/dL and decreased to 0.8 mg/dL ater a percutaneous nephrostomy tube was placed.
B. Let kidney (arrow) and associated hydronephrosis (asterisk) are again noted in this axial plane image from the same patient.
Partial ureteral obstruction may be accompanied by fluid retention and significant hypertension. When the obstructive uropathy is relieved, diuresis ensues and hypertension dissipates. In our experience, women with previous urinary tract surgery for reflux are more likely to have such obstructions.
Although infrequently complicating pregnancy, this type of diverticulum originates from an enlarging paraurethral gland abscess that ruptures into the urethral lumen. As infection clears, the remaining dilated diverticular sac and its ostium into the urethra persist. Urine collecting within and dribbling from the sac, pain, a palpable mass, and recurrent urinary infections may be associated findings. In general, a diverticulum is managed expectantly during pregnancy. Rarely, drainage may be necessary, or surgery required (Iyer, 2013). If additional antepartum evaluation is needed, MR imaging is preferred for its superior soft tissue resolution and ability to deine complex diverticula (Dwarkasing, 2011; Pathi, 2013) .