I now have sufficient information from the textbooks and web sources to give a complete, authoritative answer. Let me compile the final response.

Here is a detailed breakdown of each statement:

Physiological midgut herniation is a normal embryological event. Between weeks 6-10 of gestation, rapid elongation of the midgut (and the relatively large size of the embryonic liver) causes intestinal loops to protrude into the base of the umbilical cord. The gut then rotates 270° counterclockwise around the superior mesenteric artery axis and returns to the abdominal cavity, normally completing by ~10-12 weeks. As confirmed in Creasy & Resnik's Maternal-Fetal Medicine: "Physiologic midgut herniation of bowel into the base of the umbilical cord begins in the embryonic period and is usually complete by the time the crown-rump length reaches 45-54 mm."

The transverse (anteroposterior) measurement of the herniated gut mass must not exceed 7 mm. Sources confirm: "transverse measurements of the midgut herniation should not exceed 7 mm at any gestation." Normal physiological herniation typically measures between 4-7 mm. A mass exceeding this threshold raises concern for a true omphalocele.

This is a well-established teaching point. Creasy & Resnik's explicitly states: "Liver identified in the base of the umbilical cord is always abnormal and consistent with an abdominal wall defect." Physiological herniation contains only bowel - never solid organs. If liver is seen herniated into the cord at ANY gestational age, this is pathological (an omphalocele or abdominal wall defect).

This statement is misleading in two ways. First, the 7-mm measurement criterion is used in the first trimester context (6-12 weeks), during which physiological herniation can normally be seen. After 12 weeks (or CRL >45-54 mm), no herniation should be present at all - so the "7-mm limit" becomes irrelevant after that point; any herniation after 12 weeks is abnormal regardless of size. The limit is therefore not applicable "irrespective of gestational age" - it is specifically a first-trimester criterion.

Normal physiological herniation measures 4-7 mm. A measurement of 15 mm would be far outside normal limits and would be classified as pathological (consistent with an omphalocele). There is no evidence in the literature that 15 mm represents a normal upper limit.