Fetal bladder outlet obstruction

Case contributed by Dennis Odhiambo Agolah
Diagnosis almost certain


Sure of dates but with disparity in fetal growth (by dates -forty one weeks; by fundal height - thirty six weeks. Reports being told the fetus was diagnosed with distended bowel loops.

Patient Data

Age: 25 Years
Gender: Female

The images show a keyhole sign, indicating a distended fetal urinary bladder and urethra.

The fetal pre-micturation bladder volume amounts into 37.96 ml and no voiding visualized during the entire scan period. The fetal right kidney and ureter appears hydroureteronephrotic. There is also a widened biparietal distance with foreshortening of the occipital-frontal distance pointing towards fetal brachicephaly.

Marked oligohydramnios is present (single deepest pocket measures 1.13 cm). Doppler velocimetry of the middle cerebral artery demonstrates paradoxically low arterial resistive index at 0.52 compared with that of the umbilical arterial resistive index (0.59).

Case Discussion

This case shows fetal bladder outlet obstruction. When this is seen, it is often in males and attributable to posterior urethral valves (PUV). This, however, is extremely rare in females, if it has ever occurred, so this suggests some other cause for the urethral outlet obstruction.

Targeted imaging for fetal anomalies (TIFFA), demonstrates a normal fetal gastric bubble. The fetal urinary bladder, albeit shows a keyhole deformity and is overstretched, with a right sided Grade IV ureterohydronephrosis.

There is marked oligohydramnios.

The widened biparietal diameter divided by the occipital-frontal diameter x 100, gives a cephalic index (CI) of 94.82 (normal range at this gestation = 70.00-86.00) suggesting brachicephaly. Normal ranges in existing literature is 74-831. Low middle cerebral artery resistive index compared with umbilical artery RI noted is paradoxical and shows early fetal brain sparing/hypoxia. Features of asymmetric fetal growth restriction (IUGR) is not excluded either.

The baby succumbed one day post delivery with post emergency clinical notes showing the baby being a female with a birth weight of 1.780 kilograms. Other post delivery findings included: cleft palate, cleft lip and brachicephaly.

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