Gastroschisis in Fetal Development and the Rising Rates of Prevalence

By: Jana Andersson

Gastroschisis (gas-troh-skee-sis) may not be a term you are familiar with until you or someone you know has been given this terrifying diagnosis. While the better news is that in most cases with access to modern care this otherwise lethal condition is highly treatable. But the alarm call to all is that the prevalence of gastroschisis is on the rise. The cause of the disease remains unknown as does the reason for its increase. The following provides an overview of this congenital birth defect and also serves to increase public awareness and concern.

What is gastroschisis?

Gastroschisis belongs in the category of  “ventral wall defects” (ventral meaning “front of abdomen”) and is the most common disease in this class. Due to a malformation of the abdominal wall just to the right of the umbilical insertion the fetal intestines extrudes into the amniotic fluid. The event is generally isolated with rare instances of accompanying birth defects and few instances of genetic or chromosomal abnormalities. However, the number of new cases of has been markedly increasing. Gastroschisis is fatal without access to modern treatment. With treatment the survival rate is 95%.

Image Courtesy of the Centers for Disease Control and Prevention, National Center on Birth Defects and Developmental Disabilities

How is gastroschisis diagnosed?

Gastroschisis may be diagnosed by pregnancy screenings in the 2^nd trimester. Due to the abdominal wall defect Alpha-fetoprotein (AFP) from the fetus is released into the amniotic fluid and crosses the placenta. The elevated levels in maternal blood will register on a blood test in 77-100 % of cases. A follow up ultrasound may identify gastroschisis. Additionally, a routine 2^nd trimester ultrasound may independently diagnose the condition if no blood-work was performed or if previous levels were undetectable. There are no other maternal signs or symptoms.

Fetal signs in utero

·       AFP released into amnion from fetal tissues.

·       Sections of bowel float free in the amniotic sac and may include other organs.

·       In early pregnancy the bowel is of normal size but later the diameter may increase leading to obstruction, perforation, and lack of blood-flow.

·       Due to exposure the bowel may become irritated causing it to shorten, twist, or swell.

·       Primary nutrient loss is from membrane and muscular dysfunction.

·       Growth restriction occurs in 38-77% of cases

·       48% of fetuses/births are small size

·       Shortened gestation period of 35-37 weeks (40 is normal)

Treatment begins immediately after birth

Actions include:

·       Placement of IV for antibiotics, pain relief, and nutrition

·       Access to ventilator

·       Insertion of nasogastric tube to decompress/draw out bowel contents which could otherwise be taken up into the lungs.

·       Maintaining a temperature controlled environment

·       Maintaining sterile conditions

If the the amount of exposed bowel is small the organ can be put back in and the hole sutured within a day of birth.

If the amount of exposed bowel is large it may be repaired in stages. In such cases the intestines are put into a sterile plastic cylindrical bag called a silo. Utilizing spring tension the base of the bag seats tightly around the abdominal opening and the top of the bag mounts to a hook and is suspended over the infant much like an IV drip. The intestinal feed works by gravity and every 48 hours physical pressure is applied to the bag with a twist from the top. Over the course of 7-10 days a once large and swollen herniation will eventually fit back inside the cavity. The surgeon will then remove the silo and close up the wound.

The next challenge is recovery. The intestines may delay in working. Furthermore infants may experience disinterest in feeding, reflux, serious infections, and areas of intestinal death. Ultimately babies go home when they are feeding entirely by mouth, gaining weight and intestinal function has returned. The best case scenario for hospitalization is about a month but this can extend up to four.

Many afflicted infants go on to lead normal lives but 40% will need additional treatment at some point. Gastroschisis is the leading cause of intestinal transplantation.

What causes gastroschisis and why is there a hole in the abdominal wall to the right of the cord insertion?

The cause for gastroschisis is unknown. In normal early development the primitive gut evolves from the yolk sac and becomes the midgut – basically a long narrow tube. Thereafter this tube elongates faster than the embryonic body which forces an embryonic loop into the amnion. Later, this loop recedes back into abdomen. Earlier but in a different area of development the right umbilical vein regresses and dissolves in order to make way for an improved vascular system required for expanding growth. In gastroschisis the vascular disruption theory suggests a premature withdrawal of this right side umbilical vein before 28-32 conceptual days may lead to ischemia (cell death due to lack of blood flow) thereby adversely affecting the early evolving tissues that ultimately give rise to the abdominal defect specific to that region. Similarly it is also thought that ischemic injury to the mesenteric artery gives rise to the high rates of intestinal artresia (intestinal death) associated with gastroschisis.

What is the risk of having a baby with this birth defect?

According to the CDC

Cases per Births: 1 in 2,229

Estimated Annual Cases: 1871

·       Since the 1980s, the number of babies born with gastroschisis has increased, especially among young mothers aged younger than 20 years.

·       Between 1995-2005 cases of gastroschisis nearly doubled.

·       The prevalence of gastroschisis increased from 1995 to 2012 among mothers in every age group and for each racial/ethnic group that was studied (non-Hispanic whites, non-Hispanic blacks, and Hispanics).

FIGURE. Trends in gastroschisis prevalence, by maternal age group — 14 states,* 1995–2012

Graph image: CDC, Morbidity Mortality Weekly Report Weekly / January 22, 2016 / 65(2);23–26

Can gastroschisis be prevented?

Because the cause is unknown prevention is difficult to identify. Risk lessens after maternal age 25. Furthermore use of vasoconstrictors such as aspirin, ibuprofen, nasal decongestants, alcohol, and cigarettes during the first trimester of pregnancy can be related to the vascular pathology of the disease. More research is needed to explore genetic and environmental influences.

References

  

Ali Nawaz Khan, Sunaira Macdonald, Duree Sabih. 2015 Sept 25. Gastroschisis. Available from http://emedicine.medscape.com/article/403800-overview#a1

Chabra, Shilpi, Gleeson, Christine A.. 2006. Gastroschisis: Embryology, Pathogenesis, Epidemiology. NeoReviews Vol 6 No 11. Retrieved from: http://pedsurg.com.pe/Gastroquisis%20embriologia %20patogenesis%20y%20epidemiologia.pdf

Debich-Spicer, Diane E., Gilbert-Barness, Enid. Embryo and Fetal Pathology. 2004 May 31. Retrieved from: https://books.google.com/books?id=os_NQOiTu_4C&pg=PA510&lpg=PA510&dq=embryo+involution+veins+arteries&source=bl&ots=BX5Mji-ayl&sig=U3tknYr_vRr-hDyHdYqXAi5P8fg&hl=en&sa=X&ved=0ahUKEwif-suajuzKAhVU72MKHbsjCPMQ6AEIKjAD#v=onepage&q=embryo%20involution%20veins%20arteries&f=false

Facts about gastroschisis 2015 Nov 12. Retrieved from: http://www.cdc.gov/ncbddd/birthdefects/gastroschisis.html

Feldkamp, M. L., Carey, J. C. and Sadler, T. W. (2007), Development of gastroschisis: Review of hypotheses, a novel hypothesis, and implications for research. Am. J. Med. Genet., 143A: 639– 652. doi: 10.1002/ajmg.a.31578 Retreived from: http://onlinelibrary.wiley.com/doi/10.1002/ajmg.a.31578/abstract
Glasser, James G.. 2015 April 28. Pediatric Omphalocele and Gastroschisis. Retrieved from: http://emedicine.medscape.com/article/975583-overview

Ionescu, S., Mocanu, M., Andrei, B., Bunea, B., Carstoveanu, C., Gurita, A., ... & Selleh, M. (2014). General Report. Chirurgia, 109, 7-14. http://www.revistachirurgia.ro/pdfs/2014-1-7.pdf

Jones AM, Isenburg J, Salemi JL, et al. Increasing Prevalence of Gastroschisis — 14 States, 1995–2012. MMWR Morb Mortal Wkly Rep 2016;65:23–26. DOI: http://dx.doi.org/10.15585/mmwr.mm6502a2.
Key findings: gastroschisis – a serious birth defect - continues to increase. 2016 Jan 21. Retrieved from: http://www.cdc.gov/ncbddd/birthdefects/features/keyfindings-gastroschisis-increase.html
Key Findings: Updated National Birth Prevalence Estimates for Selected Birth Defects in the United States, 2004-2006. Reviewed 2016 Jan 21. Retrieved from: http://www.cdc.gov/ncbddd/birthdefects/features/birthdefects-keyfindings.html

National Library of Medicine (US). Genetics Home Reference [Internet]. Bethesda (MD): The Library; 2016 Feb 08. Abdominal Wall Defect; [reviewed 2012 Aug]. Available from: http://ghr.nlm.nih.gov/condition/abdominal-wall-defect

The Children's Hospital of Philadelphia (Producer). (2011, July 01) Inside out: understanding abdominal wall defects (AWD) [Video transcript] http://www.chop.edu/video/inside-out-understanding-abdominal-wall-defects-awd#.Vr9tD-YYFKm

Thomas, Kayle. Gastroschisis. Retrieved from http://averysangels.org/gastroschisis/