# Impotence and Sterility

> Impotence and sterility in MBBS Forensic Medicine — causes, examination, semen analysis, artificial insemination and medico-legal aspects.

- Canonical URL: https://prepelephant.com/topics/mbbs/forensic-medicine/impotence-and-sterility-ml
- Exam / course: MBBS · Subject: Forensic Medicine
- Publisher: PrepElephant (https://prepelephant.com) — Prepared and reviewed by the PrepElephant Academic Review Team
- First published: 2026-10-02
- Last updated: 2026-10-02
- How to cite: "Impotence and Sterility", PrepElephant, https://prepelephant.com/topics/mbbs/forensic-medicine/impotence-and-sterility-ml

## Direct answer

Impotence is the inability to perform the sexual act; sterility is the inability to reproduce. A person may be potent but sterile, or impotent yet fertile, so the two are never interchangeable. Causes are physical — developmental, endocrine, neurological, vascular or local genital disease — or psychological. Assessment needs a full history, general and genital examination, hormonal tests and semen analysis in the male. Medico-legally these questions arise in nullity of marriage, disputed paternity, rape and sexual assault defences, and artificial insemination without consent.

## What you must remember

- **Definitions:** impotence in the male is persistent inability to achieve or maintain erection sufficient for penetration; sterility is inability to beget or conceive children despite potency.
- **Male causes:** congenital maldevelopment or undescended testes; endocrine disease such as diabetes and hypogonadism; local conditions — phimosis, Peyronie disease, epididymo-orchitis; neurological disease; drugs including alcohol and opioids; and psychological causes, which are common.
- **Female causes:** developmental anomalies of vagina or uterus, endocrine disorders including polycystic ovarian disease, tubal blockage and chronic pelvic infection; vaginismus prevents intercourse but not fertility.
- **Work-up:** secondary sexual characters, genital examination, hormone profile including testosterone and prolactin, and semen analysis after two to three days of abstinence — count, motility and morphology; azoospermia proves sterility, but no laboratory test proves impotence.
- **Nullity of marriage:** impotence existing at the time of marriage and incurable is a ground for annulment; sterility alone is not.
- **Criminal cases:** an accused in a sexual assault case may plead impotence, and the court directs examination for potency; the doctor assesses on history and examination, never concluding capacity from anatomy alone.
- **Artificial insemination:** governed by the assisted reproductive technology legislation of 2021; insemination of a woman without her consent, or with donor semen without the husband's consent, is actionable; written informed consent of both spouses is mandatory.

## Common confusion

The examiner's favourite trap is the interchangeable use of the terms. A man with normal erections but azoospermia is potent yet sterile; a paraplegic may be impotent yet father a child by assisted reproduction. Equally, no test proves potency — it is a functional conclusion drawn from history, often with court-directed examination.

## Exam-focused takeaway

Examiners ask the difference with examples, the causes and work-up of impotence, interpretation of a semen report, the ground for annulment, and the rules on artificial insemination. MCQs test that impotence, not sterility, annuls a marriage, and the abstinence requirement for semen analysis. In viva, describe examining an accused pleading impotence and counselling a couple seeking assisted reproduction.

## Frequently asked questions

### What is the difference between impotence and sterility?

Impotence is inability to perform intercourse; sterility is inability to beget or conceive children — a person may be potent but sterile, or impotent yet fertile.

### Which is a ground for annulment of marriage?

Incurable impotence existing at the time of marriage; sterility alone is generally not a ground for nullity or divorce.

### How is male potency assessed?

By detailed sexual and medical history, general and genital examination, and endocrine or vascular tests as indicated; no single laboratory test proves potency.

### What makes a semen analysis reliable?

A sample given after two to three days of abstinence, examined within an hour, with at least two samples weeks apart assessing volume, count, motility and morphology.

### What is vaginismus?

Involuntary spasm of vaginal muscles preventing intercourse despite normal anatomy and fertility — a psychological cause of female impotence.

### When does artificial insemination become a legal problem?

When done without the informed written consent of the woman or her husband, or outside the statutory requirements, it becomes actionable in family law.