Isolated hypoplasia of the abdominal wall associated with fetal parvovirus B19 infection

BACKGROUND

Isolated hypoplasia of the abdominal muscles (IHAM) is a rarely reported variant of congenital abdominal wall anomalies.1 It was first described in the German literature in 1839 by Frohlich as a distinctive abdomen characterised by a bulging, lax and thin abdominal wall with usually visible intestinal peristalsis. The flanks are usually distended with wrinkled skin over the abdomen. The anterior abdominal muscle is the one commonly involved, and the aetiology is still unknown.2

Parvovirus B19 (P-B19) is a single-strand DNA virus that has an intrauterine transmission of 17%–33%. Although the majority (88.5%) of infected fetuses have spontaneous resolution without severe sequala, fetal P-B19 infection can result in hydrops fetalis (8.9%) or fetal loss (2.9%) by targeting the erythroid progenitor cell line, which will lead to anaemia and/or cardiac failure. Although P-B19 does not appear to increase the risk of congenital anomalies, multiple case reports in the literature suspected otherwise.1 2

In this article, we report a case of a preterm female that was born after hydrops fetalis associated with fetal P-B19 infection and presented with congenital hypoplasia of the abdominal muscles. This patient has been followed up for 10 years with persistent laxity of the abdominal wall.

Case presentation

A 2930 g preterm girl was born at the 35th week by elective caesarean section to a gravida 3, para 2+0. During routine antenatal visits, particularly on the 20th week of pregnancy, fetal ascites was discovered, and TORCH screen (toxoplasmosis, rubella,cytomegalovirus, herpes simplex, and other organisms) revealed positive P-B-19 infection with positive IgM on maternal blood, while Epstein-Barr virus (EBV) serology was negative. PCR for P-B-19 was positive on maternal blood. The fetus had severe anaemia (increased peak velocity of systolic blood flow in the middle cerebral artery on Doppler US and fetal haemoglobin (Hb) level of 60 g/L), required intrauterine transfusion of three packed of red blood cells (RBCs) and was complicated by hydrops fetalis. The hydrops then resolved and left only a huge ascites (figure 1).

Figure 1

Fetal ultrasound.

On delivery, her Apgar score was 7 and 8 at 1 min and 5 min, respectively. On physical examination, the baby was active with no dysmorphic features. She had an equal air entry bilaterally on mechanical ventilation, and her abdomen was hugely distended and tense.

Investigations

Complete blood count revealed a Hb level of 112 g/L, white blood cells of 12.7×10⁹/L, and platelets of 64×10⁹/L . Her liver profile showed AST level of 121 IU/L, ALT level of 21 IU/L, serum bilirubin of 130 mg/dL and albumin of 21 g/dL. Her blood gas showed a pH of 7.32, pCO₂ of 7.17 mm Hg and bicarbonate of 27.1 mEq/L. TORCH screening was negative except for herpes simplex virus IgG. Furthermore, EBV and P-B19 IgG(s) were positive.

Chest and abdominal X-ray showed severely distended abdomen with huge ascites and small lung due to chest compression (figure 2). Abdominal US showed huge ascites and subcutaneous oedema of the abdominal wall (figure 3)(Figure 3 ). Head US and ECG were unremarkable. Glucose challenge test was negative, and glucose-6-phosphate dehydrogenase (G6PD) level was normal.

Figure 2

Chest and abdominal X-ray.

Figure 3

Abdominal ultrasound on admission.

Differential diagnosis

Prune-Belly syndrome is a rare multisystem condition typically characterised by deficient or absent abdominal wall musculature, bilateral intraabdominal cryptorchidism and urinary tract anomalies, including megalourethra, megacystis, hydroureteronephrosis and renal dysplasia, which is not in our case.

Treatment

Following the delivery, the baby was immediately intubated and abdominal paracentesis was done to drain 20 mL of the peritoneal fluid and replace it with 20 mL of normal saline. Thirty-five millilitre of RBCs were transfused over 4 hours until Hb was stabilised at 171 g/L. Another abdominal paracentesis was done to remove 200 mL of the peritoneal fluid, and replaced by normal saline over 1 hour.

Phototherapy was started when the baby jaundiced and was discontinued when serum bilirubin became in the observation level at 164 mg/dL. A third abdominal paracentesis was done and drained 300 mL and replaced by 100 mL of normal saline.

Outcome and follow-up

The baby’s Hb responded well to the RBCs transfusion. Her Hb increased slowly and reached 190 g/L. The platelets dropped to 30×10⁹/L and then increased to 53×10⁹/L.

She started feeding on the third day, which was well tolerated. She was observed until day 8 of life at which she was discharged in a good condition.

After 1 month, she attended the neonatology follow-up, and the thrombocytopenia was resolved. Her abdomen was soft, but the distention was still evident. she was otherwise normal and stable. She came later for the 2 month’s vaccine. The baby showed normal growth parameters and psychomotor development, yet the distention was still noticed. At 4 month’s vaccine appointment, there was no active issue and her abdomen was soft and lax.

Within the course of 10 years follow-up, she was developmentally fine, but the distention of the abdomen still existed (figure 4). An abdominal MRI confirmed significant muscle weakness and thinning in the anterior and lateral abdominal wall. The MRI was otherwise unremarkable.

Figure 4

Abdominal wall images.