Narrowest part of the fallopian tube is the?

Appeared in: NHM UP Staff Nurse - 2017

Explanation

The interstitial portion, also known as the intramural part, is the segment of the fallopian tube that passes through the muscular wall of the uterus.
This section is the shortest, measuring about 1 cm in length.
Its lumen is the most constricted, with a diameter of approximately 1 mm, making it the narrowest part of the entire fallopian tube.

Option A: The ampulla is the widest and longest part of the fallopian tube, not the narrowest.
Option B: While the isthmus is a narrow, thick-walled portion of the tube, it is not the narrowest segment. The interstitial portion is more constricted.
Option C: The infundibulum is the funnel-shaped opening of the fallopian tube near the ovary. It is characterized by its fimbriae and is not the narrowest part.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Anatomy of the Fallopian Tube as background academic context rather than a clinical decision trigger.
Understanding the detailed anatomy of the fallopian tube is crucial for nurses in obstetrics and gynecology to assess and manage conditions like ectopic pregnancy and infertility.
An ectopic pregnancy in the narrow interstitial portion is a high-risk emergency. A nurse must be vigilant for signs of rupture, such as severe unilateral abdominal pain, shoulder tip pain (Kehr's sign), and hypovolemic shock (tachycardia, hypotension), as rupture can lead to massive hemorrhage.
What if? If a patient has a history of Pelvic Inflammatory Disease (PID), the risk of tubal scarring increases. This scarring can narrow or block any part of the tube, but if it affects the interstitial portion, it significantly raises the risk of both infertility and a dangerous interstitial ectopic pregnancy.

How to Approach the Question

This is a factual recall question based on anatomy.
First, identify the core of the question: it asks for the 'narrowest part' of the 'fallopian tube'.
Mentally review the four segments of the fallopian tube, typically in order from the ovary to the uterus: Infundibulum, Ampulla, Isthmus, and Interstitial (Intramural) part.
Compare the relative sizes of these segments. Recall that the ampulla is the widest, the isthmus is narrow, and the interstitial part is the segment that passes through the dense uterine wall.
Conclude that the passage through the uterine muscle makes the interstitial portion the most constricted or narrowest part.
Select the option that matches this anatomical fact.

Concept Tested & Keywords

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E6 Anatomy Applied Ashalatha 4e p. 389-391

Practise the full NHM UP Staff Nurse - 2017

Attempt every question from this paper in a timed mock, then review the full solution for each one.