Incidence: 1 in 6000 live births present in the first week of life. Can go undiagnosed until later in life if asymptomatic, but 80% of all cases of malrotation present in the first month of life.

45 times more common in Down Syndrome.

Cause: Incomplete bowel rotation during the 7^th-12^th week of gestation. Abnormally rotated bowel is unable to form a normal mesenteric attachment. Therefore the mesenteric attachment is frequently short, and this allows it to twist around the superior mesenteric vessels and obstruct and infarct the small and large intestine.

Age at onset: 3-7 days of age

Presentation: Bilious Vomiting, rapid deterioration with haemodynamic instability, metabolic acidosis and raised lactate if not managed promptly

Diagnostic findings: Upper GI spiral sign on USS. Abnormal location of superior mesenteric vessels (Kimura K, 2000), abnormal location of duodenal-jejunal (DJ) flexure seen on upper GI contrast (should normally be sited to the left of the spine at the same level or higher than the pylorus) “Corckscrew” sign on contrast due to incomplete obstruction with some contrast passing through. (H, 2007) AXR will frequently be normal

Management: Ladds procedure which involves untwisting the bowel, resecting any ischaemic / non viable bowel tissue. The duodenum is straightened and the small bowel is placed on the right side with the large bowel mostly on the left which stabilises the bowel. (H, 2007)

“Spiral sign” in malrotation: Duodenum and Proximal Jejunum have a Spiral configuration and are located in the right side of the abdomen. (H, 2007)

“Corkscrew” Sign of malrotation with midgut volvulus. Barium study showing a corkscrew appearance of the fourth portion of the duodenum and proximal jejunum and abnormal position of the DJ flexure.

Case courtesy of Behrang Amini, Radiopaedia.org. From the case rID: 35920

Barium meal demonstrating malrotation. There is abnormal distribution of the small bowel. The duodenum does not cross the midline and the DJ flexure is at the level of L3 (too low). The small bowel is also curled on the right side of the abdomen with colon on the left.

Case courtesy of Frank Gaillard, Radiopaedia.org. From the case rID: 8029

Incidence: 1 in 5000 live births. 25% of infants with duodenal atresia have Down Syndrome

Cause: Failure of recanalisation of the duodenum, resulting in a congenital obstruction of the second portion of the duodenum. There may be a membranous or interrupted type lesion at the level of the Papilla of Vater. In 80% of these patients the Papilla of Vater opens in the proximal duodenum which is the reason for the bilious vomiting. (Kimura, K 2000)

Age at Onset: Few hours of age. Often diagnosed antenatally,

Presentation: History of polyhydramnios in the neonatal period +/- high risk pregnancy for Down Syndrome. Bilious vomiting, feed intolerance.

Diagnostic Findings: Double bubble sign on AXR.

Management: Interrupted lesions are managed with Duodeno-duodenostomy or duodeno-jejunostomy, which is where the proximal portion of the duodenum is mobilised and connected to the next patent portion of duodenum or jejunum, bypassing the obstruction. Membranous lesions are managed by removing the obstructing membrane

Barium study demonstrating duodenal atresia. There is no contrast passing beyond the duodenal bulb

Case courtesy of Hani Makky Al Salam, Radiopaedia.org. From the case rID: 9357

Abdominal X-Ray in a neonate who is intubated and has umbilical lines in situ. There is marked gaseous distension of the stomach and proximal duodenum with absent bowel gas distally. “Double Bubble” sign

Case courtesy of Alexandra Stanislavsky, Radiopaedia.org. From the case rID: 47635

Abdominal X-ray in a neonate demonstrating enlarged gastric and duodenal gas shadows. “Double Bubble” sign

Case courtesy of Farid Rajaee Rizi, Radiopaedia.org. From the case rID: 156737

Incidence: 1 in 5000-1 in 14,000 live births

Cause: A mesenteric vascular accident occurs in the foetus which results in infarction of a segment of intestine. There are 4 different types of jejunoileal atresia (apple-peel, membranous, interrupted and multiple) but all present in the same way. (Kimura, K 2000)

Age at Onset: Within the first 24 hours of life. The more proximal the lesion, the earlier the baby will present with bilious vomiting

Presentation: Abdominal distension, bilious vomiting, feed intolerance. These babies may initially pass meconium and then have difficulty opening their bowels, so do not be reassured if there is a history of having passed meconium

Diagnostic Findings: Abdominal X-Ray shows air fluid levels proximal to the obstruction. There may be a triple bubble sign if the obstruction is proximal.

Management: Depends on the location of the atresia but generally end-to-end anastamosis allows for bowel reconstuction, similar to the duodeno-duodenostomy.

Abdominal X-Ray in a neonate demonstrating gaseous, distended bowel loops with multiple air fluid levels which suggests a lower intestine atresia

(Kimura, K 2000)

Abdominal X-Ray of a neonate which shows large distended bowel loops with an abrupt cut off at the level of the distal duodenum / proximal jejunum, indicative of small bowel atresia. The tip of an NG tube can be seen in the stomach bubble

Case courtesy of Hani Makky Al Salam, Radiopaedia.org. From the case rID: 7569

Incidence: 1 in 5000- 10,000 live births. Occurs in 15% of babies with cystic fibrosis. 80-90% of babies with a meconium ileus have cystic fibrosis.

Cause: Retention of thick meconium in the bowel resulting in obstruction. This exists in two forms: Simple meconium ileus and complex meconium ileus.

Simple meconium ileus: the meconium obstructs the terminal ileum, and small intestine proximal to the site of obstruction becomes distended with meconium, air and fluid.

Complex meconium ileus: meconium distended segments of small intestine may predispose to complications antenatally such as volvulus, ischaemia and necrosis, intestinal atresia and perforation. (Parikh NS, 2023)

Meconium ileus mostly occurs in cystic fibrosis because of the mutation that affects the CFTR. In the small intestine the CFTR excretes chloride and bicarbonate. Bicarbonate usually has a role in chelating calcium which helps to regulate the acidity of the gut and form normal, loose mucous. Abnormal bicarbonate secretion due to CFTR mutation causes an acidic and dehydrated environment which results in thick, viscous mucous that forms thick meconium that can then obstruct the lumen. (Sathe M, 2017)

Age at onset: Often diagnosed antenatally, but if not presents within a few hours of birth

Presentation: Abdominal distension, failure to pass meconium, bilious vomiting. Thickened bowel loops can be visible and palpable through the abdominal wall

Diagnostic Findings: Antenatal USS may demonstrate hyperechoic masses which is the inspissated meconium in the terminal ileum. Postnatally, abdominal X-Ray will demonstrate dilated loops of bowel +/- air fluid levels. If there have been further complications such as perforation with meconium extruding into the peritoneum there may be calcifications visible on AXR. The “soap bubble” sign may be present which is a result of air and meconium mixing. A contrast enema will show a microcolon due to disuse below the obstructed small intestine. Sweat test and genetic testing confirm cystic fibrosis diagnosis.

Management: If there is no evidence of perforation or bowel ischaemia then meconium ileus can be managed medically with a hyperosmolar enema – Gastrograffin. This works by shifting fluid into the bowel lumen through osmosis and breaking up the meconium obstruction. Some centres then use N-Acetyl cysteine via NGT every 6 hours to continue to dissolve meconium distal to the original obstruction. Medical management is successful in 30-80%.

In complex meconium ileus or if medical management is unsuccessful, surgical management is required. This is usually in the form of warm saline irrigation of the terminal ileum / gastrograffin enema in theatre for disimpaction with subsequent ileostomy formation. (Sathe M, 2017)

Barium enema in a neonate demonstrating a diffuse microcolon secondary to meconium ileus.

Case courtesy of The Radswiki, Radiopaedia.org. From the case rID: 11601

AXR of a neonate with meconium ileus demonstrating multiple distended loops of bowel indicative of small bowel obstruction, with a soap ubble appearance seen to the right

(Hekmatnia A, 2023)

Abdominal X-ray of a neonate with an arrow pointing to an area of increased opacity on the right side which is calcification secondary to meconium peritonitis after a perforation antenatally

(Ebigbo N, 2017)

Incidence: 1 in 500 live births. 40% of cases are associated with Hirschprungs and 40% are associated with cystic fibrosis. There has also be a reported link between maternal diabetes and an increased risk of meconium plug.

Cause: Obstruction due to an inspissated plug of meconium. Caused by inadequate peristalsis due to immature myenteric nervous system. (L, 2018). Usually transient and affects the left colon with meconium plugging bowel distal to this.

Age at Onset: 1-2 days old

Presentation: Abdominal distension, delayed passage of meconium for 24-48 hours, bilious vomiting

Diagnostic Findings: Abdominal X-Ray may show non-specific findings of multiple dilated bowel loops proximal to the obstruction. Contrast enema may show a small caliber left colon with multiple filling defects due to meconium plugs.

Management: Many cases resolve spontaneously or can be managed medically with water soluble contrast enema.

Contrast enema demonstrating a small caliber left colon secondary to meconium plug.

Case courtesy of The Radswiki, Radiopaedia.org. From the case rID: 11941

Abdominal X-ray in a neonate showing non-specific appearances of dilated bowel loops indicative of obstruction secondary to meconium plugs.

Case courtesy of Jeremy Jones, Radiopaedia.org. From the case rID: 62796

Incidence: 2.4 in 1000 live births. Babies born preterm / low birth weight are at a much higher risk of developing necrotising enterocolitis (NEC)

Cause: Infection and inflammation in the gut that can progress and result in necrosis and perforation. Increased risk in growth restricted infants, premature babies, maternal drug abuse, formula fed babies, infants receiving blood transfusions.

Age at Onset: Typically presents around 2-3 weeks old but can present earlier or later than this.

Presentation: Abdominal distension and discolouration, bilious vomiting, apnoeas and bradycardias, temperature instability, blood in stool, haemodynamic instability

Diagnostic Findings: High CRP, raised lactate, metabolic or mixed acidosis, thrombocytopaenia, anaemia. Pneumatosis intestinalis on abdominal X-Ray, gaseous distended bowel loops, featureless bowel, air in the portal vein. There may be evidence of perforation on AXR.

An abdominal x-ray showing extensive pneumatosis intestinalis which occurs as a result of intraluminal (yellow stars) and intramural gas (blue arrows).

Case courtesy of Hani Makky Al Salam, Radiopaedia.org. From the case rID: 9793

Chest and abdominal X-ray of a neonate who is intubated with an NG tube in situ. The cyan circle is an area of portal venous gas and the magenta outline is around pneumatosis. Both are evidence of NEC

Case courtesy of Rad_doc, Radiopaedia.org. From the case rID: 47589

Abdominal X-ray of a neonate with the tip of the NG tube visible, a urinary catheter in the bladder and the tip of a right femoral vein.

Appearances of widespread gas filled loops of bowel which is very suspicious for NEC

Case courtesy of Jeremy Jones, Radiopaedia.org. From the case rID: 62793

Incidence: 1 in 5000 live births. Increased incidence in infants with Down syndrome. Other syndromes associated with Hirschsprung’s disease include Waardenburg syndrome, Mowat-Wilson syndrome, Bardet-Biedel syndrome, multiple endocrine neoplasia type 2, Smith-Lemli Opitz syndrome

Causes: Failure of the parasympathetic nervous system to migrate caudally in the intestine results in aganglionosis of the rectum +/- the colon. Hirschsprung’s can be classified as short segment, long segment or total colon aganglionosis.

Short segment affects the recto-sigmoid section of the colon and is the most prevalent form of Hirschprung’s affecting 80%. Long segment affects proximal sigmoid colon in 15%, and total colonic aganglionosis affects the entire colon in up to 5%. (Rajabally F, 2023)

Age at onset: Presents at 2-4 days of age

Presentation: Failure to pass meconium in first 24-48 hours, abdominal distension (90%), bilious vomiting (85%), poor feeding. Can present with complications such as obstruction, intestinal perforation or enterocolitis. There may be dysmorphic features in keeping with an associated syndrome

Diagnostic findings: Diagnosed with rectal suction biopsy which can be done without anaesthetic in the neonatal unit or in outpatients. Biopsy shows absence of parasympathetic ganglia and presence of hypertrophied nerve trunks in the bowel wall. Contrast enema demonstrates the transition zone which is an abnormally innervated section of bowel between the aganglionic bowel and normal colon.

Management: If well, babies with Hirschsprung’s can be managed in the first weeks-months of life with regular rectal washouts and later in life will have a pull through (Duhamel) procedure

Contrast enema of a neonate with Hirschsprung’s disease. This shows a dilated sigmoid colon leading to the transition zone (labelled TZ) just at the distal sigmoid and a small caliber rectum

Case courtesy of Tee Yu Jin, Radiopaedia.org. From the case rID: 71552

Abdominal x-ray of a neonate with Hirschsprung’s disease which shows dilated loops of bowel with no gas in the rectum and no free air.

Case courtesy of Craig Hacking, Radiopaedia.org. From the case rID: 73066

Incidence: 1 in 4000-5000 live births. Associated with VACTERL association (At least 3 of: Vertebral anomalies, Ano-rectal malformation, Cardiac defects, Tracheo-oesophageal fistula, Oesophageal atresia, Renal anomalies, Limb abnormalities)

Cause: Ano-rectal malformations encompasses a wide range of conditions, including imperforate anus, cloacal anomalies etc. Causes are thought to be multi-factorial and include genetics, maternal diabetes and more

Age at Onset: This should be diagnosed at birth, if missed at birth it may be diagnosed on the newborn examination or picked up with the baby becoming unwell

Presentation: If missed at birth can present with bilious vomiting, abdominal distension, feed intolerance, failure to pass meconium. (Babies with ano-rectal malformations still can pass meconium through fistulas so just because they have passed meconium, this doesn’t automatically rule out an ano-rectal malformation)

Diagnostic Findings: Can mostly be diagnosed on external examination. If there is VACTERL association there may be other findings such as horseshoe kidney on renal USS, butterfly or hemi-vertebrae on CXR/AXR, cardiac defect on echo.

Management: If there is an imperforate anus the baby will usually have a stoma formed in the first day of life and when they are larger they will have a pull through procedure to form an anus. If there is a cloacal anomaly with a fistula this is normally repaired when the child is older as long as they are passing stool. For all babies with ano-rectal malformations, renal USS, spinal USS and echo should be performed to look for VACTERL association.

Image of a baby with an Imperforate Anus and underformed buttocks.

Incidence: 22 per 1000 liver births

Cause: Most commonly group B strep which has colonised the vaginal canal. Other risk factors include prolonged rupture of membranes, preterm and maternal sepsis. Sepsis causes an ileus or functional bowel obstruction.

Age at Onset: First week of life but infants are at risk of late onset neonatal sepsis until 3 months of age

Presentation: Temperature instability, feed intolerance, sleepy, not waking for feeds, high pitched cry, full fontanelle , respiratory distress, hypotonia, grunting, hypoglycaemia.

Diagnostic Findings: High CRP, high white cell count with neutrophilia, hypoglycaemia, thrombocytopaenia, metabolic or mixed acidosis, raised lactate, positive blood culture or CSF culture. There may be consolidation on CXR

Management: Antibiotics as per local guidelines and depending on culture results. NG feeds if not feeding well. Respiratory support if chest findings +/- respiratory distress

Sometimes there is no cause found for the vomiting, investigations are normal and it self resolves.