Since blood and daily urine excretion of creatinine shows minimal fluctuation, creatinine excretion is useful in determining whether 24-hour urine specimens for other analytes (e.g., protein) have been completely and accurately collected. To view specimen requirements and codes please Select a regional laboratory.
Ultrasound is almost foolproof at diagnosing twins, but the greater the number of babies, the less accurate the ability to detect how many there are. It's possible to see twins (or more) on a scan at around six weeks, though one baby may be missed at this early stage. Sometimes a heartbeat is seen in one sac, but not in the other. Rescanning in a week or two may reveal a second heartbeat, or the scan may show that one sac is growing and the other still empty.
Twin pregnancy week 20 ultrasound. In a twin pregnancy, two babies are generally scanned separately to screen for any physical or other abnormalities. The appearance and size of the two babies is evaluated as well to make sure they both have the same growth rate [15]. Signs and symptoms at pregnancy week 20.