Question:hard
What maternal condition is associated with the fetal anomaly shown in the image below?
What maternal condition is associated with the fetal anomaly shown in the image below?
Show Hint
Absent sacrum: which diabetes is present from before conception?
Updated On: Jun 23, 2026
- ACE inhibitor use
- Gestational diabetes mellitus
- Pregestational diabetes mellitus
- Valproate use
Show Solution
The Correct Option is C
Solution and Explanation
Anomaly to cause: an absent sacrum with a stunted lower spine is caudal regression syndrome, and the classic association tested here is pregestational diabetes, roughly a 25-fold higher risk.
The reason GDM is the trap answer: gestational diabetes only develops in the second half of pregnancy, well after organogenesis is finished, so it raises macrosomia and neonatal hypoglycaemia risk but is not strongly teratogenic. Caudal regression is an early-embryo defect, so it needs hyperglycaemia present at conception, that is pregestational (overt) diabetes with poor periconceptional control.
Eliminate the drug options on their own signatures: ACE inhibitors in the second and third trimesters cause oligohydramnios, renal tubular dysgenesis and calvarial hypoplasia. Valproate is tied to neural-tube defects such as spina bifida and to cardiac and facial defects, not to an absent sacrum. On ultrasound look for the short spine ending above shield-like, close-set iliac wings. So the answer is pregestational diabetes mellitus. Ref: Williams Obstetrics, 24th ed.
The reason GDM is the trap answer: gestational diabetes only develops in the second half of pregnancy, well after organogenesis is finished, so it raises macrosomia and neonatal hypoglycaemia risk but is not strongly teratogenic. Caudal regression is an early-embryo defect, so it needs hyperglycaemia present at conception, that is pregestational (overt) diabetes with poor periconceptional control.
Eliminate the drug options on their own signatures: ACE inhibitors in the second and third trimesters cause oligohydramnios, renal tubular dysgenesis and calvarial hypoplasia. Valproate is tied to neural-tube defects such as spina bifida and to cardiac and facial defects, not to an absent sacrum. On ultrasound look for the short spine ending above shield-like, close-set iliac wings. So the answer is pregestational diabetes mellitus. Ref: Williams Obstetrics, 24th ed.
Was this answer helpful?
0
