Gastrointestinal Tract Flashcards
What are the abnormalities associated with the Gastrointestinal Tract in pregnancies?
10 Abdominal Cysts Anorectal Atresia Duodenal Atresia Oesophageal Atresia Hepatic Calcifications Hirschsprung's Disease Liver Tumours Meconium Peritonitis Not-Visible Gallbladder Small Bowel Obstruction
Abdominal Cysts
Abdominal cystic masses are frequent findings at ultrasound examination. Renal tract anomalies or dilated bowel are the most common explanations, although cystic structures may arise from the biliary tree, ovaries, mesentery or uterus. The correct diagnosis of these abnormalities may not be possible by ultrasound examination, but the most likely diagnosis is usually suggested by the position of the cyst, its relationship with other structures and the normality of other organs.
Choledochal cysts:
Choledochal cysts represent cystic dilatation of the common biliary duct. Prenatally, the diagnosis may be made ultrasonographically by the demonstration of a cyst in the upper right side of the fetal abdomen. There is communication between the bile duct and the cyst. Absence of polyhydramnios or peristalsis may help to differentiate the condition from bowel disorders. Postnatally, early diagnosis and removal of the cyst may avoid the development of biliary cirrhosis, portal hypertension, calculi formation or adenocarcinoma. The operative mortality is about 10%.
Mesenteric or omental cysts:
These cysts may represent obstructed lymphatic drainage. The fluid contents may be serous, chylous or hemorrhagic. Antenatally, the diagnosis is suggested by the finding of a multiseptate or unilocular, usually mid-line, cystic lesion of variable size; a solid appearance may be secondary to hemorrhage. Antenatal aspiration may be considered in cases of massive cysts resulting in thoracic compression. Postnatal management is conservative and surgery is reserved for cases with symptoms of bowel obstruction or acute abdominal pain following torsion or hemorrhage into a cyst. Complete excision of cysts may not be possible because of the proximity of major blood vessels and in up to 20% of cases there is recurrence after surgery. Although malignant change in mesenteric cysts has been described, this is rare.
Hepatic cysts:
Hepatic cysts are typically located in the right lobe of the liver. They are quite rare and result from obstruction of the hepatic biliary system. They appear as unilocular, intrahepatic cysts, and they are usually asymptomatic, although rarely may show complications such as infections or hemorrhages. Hepatic cysts are found in 30% of the cases of adult polycystic kidney disease.
Intestinal duplication cysts:
These are quite rare, and may be located along the entire gastrointestinal tract. They sonographically appear as tubular or cystic structures of variable size. They may be isolated or associated with other gastrointestinal malformations. Thickness of the muscular wall of the cysts and presence of peristalsis may facilitate the diagnosis. Postnatally, surgical removal is carried out.
Anorectal Atresia
Prevalence: 1 in 5,000 births.
Ultrasound: Overdistention of the rectum and sigmoid colon in the third trimester.
Normal amount of the amniotic fluid.
Occasionally, intraluminal calcifications (meconium) can be visualised.
Assoc abnorm: Chromosomal defects, mainly trisomy 21 and 18, are found in 3-4% of cases.
Other defects, mainly urogenital malformations, vertebral anomalies and CNS, are found in up to 70%
of cases.
Non-genetic syndromes: VACTERL association (sporadic; vertebral and ventricular septal defects, anal atresia, tracheoesophageal fistula, renal anomalies, radial dysplasia and single umbilical artery), Caudal regression syndrome (sporadic; sacral agenesis or hypoplasia, hypoplastic veretebral bodies, anal atresia), OEIS complex (sporadic; omphalocele, exstrophy of the cloaca, imperforate anus, and spinal defects).
Follow up: Follow-up should be standard.
Prognosis: In isolated cases the overall survival is good.
In cases presenting with multiple abnormalities the prognosis is poor.
Recurrence: No increased risk of recurrence.
Part of trisomies: 1%.
Duodenal Atresia
Prevalence: 1 in 5,000 births.
Ultrasound: ‘Double bubble’ sign as a result of an enlarged stomach and duodenal cap. Usually found >24 weeks’ gestation.
Polyhydramnios >24 weeks’ gestation in 50% of cases.
Assoc abnorm: Chromosomal defects, mainly trisomy 21, are found in 30% of cases.
Other defects, mainly cardiac, renal, vertebral, are found in 10-20% of cases.
Follow up: Ultrasound scans every 2-3 weeks to monitor growth and assess amniotic fluid volume. Amniodrainage may be necessary if there is polyhydramnios and cervical shortening.
Prognosis: Survival rate >95%.
Recurrence: Isolated: no increased risk of recurrence.
Part of trisomy 21: 1%.
Oesophageal Atresia
Prevalence: 1 in 3,000 births
Ultrasound: Small or ‘absent’ stomach in the presence of polyhydramnios >25 weeks’ gestation.
Esophageal atresia may be suspected prenatally in only about 40% of cases because if there is an associated tracheoesophageal fistula (found in >80% of cases), the stomach may look normal.
Assoc abnorm: Chromosomal defects: trisomy 18 found in 20% of cases and trisomy 21 in 1% of cases.
Other defects, mainly cardiac, found in 50% of cases.
Tracheoesophageal fistulae may be seen as part of the VACTERL association (sporadic; vertebral and ventricular septal defects, anal atresia, tracheoesophageal fistula, renal anomalies, radial dysplasia and single umbilical artery).
Follow up: Ultrasound scans every 2-3 weeks to monitor growth and assess amniotic fluid volume. Amniodrainage may be necessary if there is polyhydramnios and cervical shortening.
Prognosis: Survival is primarily dependent on gestation at delivery and the presence of other anomalies. For babies with an isolated tracheoesophageal fistula, born after 32 weeks’ gestation without aspiration pneumonitis, postoperative survival is >95%.
Recurrence: Isolated: no increased risk of recurrence.
Part of trisomies: 1%.
Hepatic Calcifications
Prevalence: 1 in 2,000 fetuses at 20 weeks’ gestation.
Ultrasound: Presence of solitary or multiple echogenic foci (1-2 mm in diameter) within the substance of the liver or in the capsule.
Assoc abnorm: The incidence of chromosomal abnormalities and genetic syndroms is not increased.
Parenchymal calcifications may be due to intrauterine infection.
Follow up: In isolated cases follow-up should be standard.
Prognosis: Good.
Recurrence: No increased risk of recurrence.
Hirschsprung’s Disease
Prevalence: 1 in 3,000 births.
Ultrasound: The condition is characterized by congenital absence of intramural parasympathetic nerve ganglia in a segment of the colon. The aganglionic segment is unable to transmit a peristaltic wave, and therefore meconium accumulates and causes dilatation of the lumen of the bowel. The ultrasound appearance is similar to that of anorectal atresia, when the affected segment is colon or rectum.
Polyhydramnios and dilatation of the loops are present in the case of small bowel involvement; on this occasion, it is not different from other types of obstruction.
Assoc abnorm: Chromosomal abnormalities, mainly trisomy 21, are found in 5% of cases.
Follow up: Ultrasound scans every 2-3 weeks to monitor the evolution of the condition and assess amniotic fluid volume. Amniodrainage may be necessary if there is polyhydramnios and cervical shortening.
Prognosis: Postnatal surgery is aimed at removing the affected segment and this may be a two-stage procedure with temporary colostomy. Neonatal mortality is approximately 20%.
Recurrence: No increased risk of recurrence.
Part of trisomy 21: 1%.
Liver Tumours
Prevalence: 1 in 100,000 births.
Ultrasound: The most common are hemangioma, mesenchymal hamartoma and hepatoblastoma.
They can be cystic, echogenic, mixed solid and cystic or they may just present with hepatomegaly.
Hemangiomas and hepatoblastomas may be associated with evidence of high-output heart failure, hydrops and polyhydramnios.
Color Doppler studies may be helpful in distinguishing hemangioma from the other tumors.
Assoc abnorm: Chromosomal abnormalities: no increased risk.
Hepatoblastoma can be associated with the Beckwith–Wiedemann syndrome with evidence of organomegaly and macroglossia.
Follow up: Ultrasound scans every 2-3 weeks to monitor the size of the tumor and development of heart failure and polyhydramnios.
Prognosis: Hemangiomas: survival of about 80% after treatment with steroids. However, occasionally, they are associated with arteriovenous shunting, congestive heart failure and hydrops, resulting in intrauterine or neonatal death. After infancy the tumors regress spontaneously.
Mesenchymal hamartoma: surgical resection with 70% survival.
Hepatoblastoma: surgical resection with 60% survival. Prior to resection several cycles of chemotherapy may be necessary to shrink the tumor and make it resectable.
Recurrence: In general there is no increased risk of recurrence.
In hepatoblastoma in association with Beckwith–Wiedemann syndrome (autosomal dominant) and familial adenomatous polyposis (autosomal dominant condition that predisposes to colonic adenomas and carcinomas) the risk is increased.
Meconium Peritonitis
Prevalence: 1 in 3,000 births
Ultrasound: Presence of intra-abdominal hyperechogenic areas (peritoneal calcifications). Results from intrauterine perforation of the bowel which leads to a local sterile chemical peritonitis.
Additionally: dilated bowel loops, ascites and meconium pseudocyst.
Assoc abnorm: The incidence of chromosomal abnormalities and genetic syndroms is not increased.
Risk of cystic fibrosis: 75%.
Follow up: Ultrasound scans every 4 weeks to monitor the evolution of the condition.
Prognosis: In case of simple peritonitis the outcome is good and surgical intervention is not necessary.
In case of complex peritonitis (associated with bowel dilatation, ascites) the prognosis is poor and neonatal mortality is >50%.
Recurrence: Isolated: no increased risk of recurrence.
Not-Visible Gallbladder
Prevalence: 1 in 1,000 fetuses at 20 weeks’ gestation.
Ultrasound: Small or absent gallbladder.
In most cases this is a transient finding (75%), but some are due to isolated gallbladder agenesis (15%), cystic fibrosis (10%) and rarely biliary atresia (3%).
Assoc abnorm: In about 25% of cases of biliary atresia there associated heterotaxy syndrome, which includes situs inversus, polysplenia, malrotation of the gut intestinal atresia and heart defects.
Follow up: Follow-up should be standard.
Prognosis: Biliary atresia is a serious condition requiring liver transplantation.
Gallbladder agenesis is a benign condition.
Recurrence: No increased risk of recurrence.
Small Bowel Obstruction
Prevalence: 1 in 5,000 births.
Ultrasound: Multiple fluid-filled loops of the bowel in the abdomen >7 mm in diameter presenting >25 weeks’ gestation.
Distension of the abdomen with active peristalsis.
If bowel perforation occurs, transient ascites, meconium peritonitis and meconium pseudocysts may ensue.
Polyhydramnios >25 weeks’ gestation, especially in proximal obstructions.
Assoc abnorm: The incidence of chromosomal abnormalities and genetic syndroms is not increased.
Other bowel anomalies: malrotation, gastroschisis, duplication and meconium ileus.
10% risk of cystic fibrosis (up to 90% in case of associated meconium peritonitis).
Follow up: Ultrasound scans every 2-3 weeks to monitor growth and assess amniotic fluid volume. Amniodrainage may be necessary if there is polyhydramnios and cervical shortening.
Prognosis: The prognosis is related to the gestational age at delivery, the presence of associated abnormalities and site of obstruction. In those born after 32 weeks with isolated obstruction requiring resection of only a short segment of bowel, survival is >95%. Loss of large segments of bowel can lead to short gut syndrome, which is a lethal condition.
Recurrence: Isolated: no increased risk of recurrence.
