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# Anterior fibromuscular stroma

The anterior fibromuscular stroma is the front surface of the [prostate](https://durgical.com/en/anatomy/prostate/), made of muscle and fibrous tissue without glands; cancer rarely starts here.

Official name: Isthmus of prostate

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## What it is

The front part of the prostate: a shield of fibrous tissue and smooth muscle with almost no glands, in front of the urethra.

## What it does

Forms the front surface of the prostate and blends with the muscle of the bladder neck above and the external sphincter below; few cancers start here.

## Key points

- A non-glandular shield, so primary cancer almost never starts here; tumours growing forward from the transition zone can invade it
- Anterior tumours near it are out of reach of the finger on rectal examination and are often missed by a standard biopsy that samples mainly the back of the gland
- The dorsal vein complex lies directly in front of it and is controlled early in radical prostatectomy to limit bleeding

## Key facts

**Where**
Anterior surface of the prostate, in front of the urethra; fibrous tissue and smooth muscle with almost no glands

**Attaches**
Blends above with bladder neck smooth muscle and below with the external urethral sphincter; the dorsal vein complex lies in front of it

**Function**
Forms the anterior wall of the gland; having no glands, it is rarely the origin of cancer

## Relations

**In front**
Retropubic space with the dorsal vein complex and the puboprostatic ligaments, then the [pubic symphysis](https://durgical.com/en/anatomy/pubic-symphysis/)

**Behind**
[Transition zone](https://durgical.com/en/anatomy/transition-zone-of-prostate/) and the [prostatic urethra](https://durgical.com/en/anatomy/prostatic-urethra-seminal-colliculus/)

**Above**
Smooth muscle of the bladder neck, with which it blends

**Below**
[External urethral sphincter](https://durgical.com/en/anatomy/female-external-urethral-sphincter/) at the prostatic apex

## On imaging

On T2-weighted MRI it is uniformly dark, which can hide an anterior tumour or be mistaken for one; radiologists compare it with the nearby transition zone and check diffusion images. Enlarging BPH nodules push against it and can thin it.

## Common problems

- Benign prostatic hyperplasia (BPH): growth with age, mainly of the transition zone, that squeezes the urethra.
- Prostate cancer, one of the most common cancers in men; most start in the [peripheral zone](https://durgical.com/en/anatomy/peripheral-zone-of-prostate/).
- Prostatitis (infection or inflammation).

## How it is diagnosed

Digital rectal examination; PSA blood test; MRI and a needle biopsy if cancer is suspected; ultrasound.

## Treatment

- Medicines for BPH (alpha-blockers, 5-alpha-reductase inhibitors); surgery through the urethra (TURP) if needed.
- Prostate cancer: active surveillance, radical prostatectomy or radiotherapy, depending on the risk.

## Clinical notes

- Anterior cancers (often transition-zone in origin) are found mainly by MRI and MRI-targeted biopsy, since rectal examination and a standard biopsy scheme can miss them
- When an anterior tumour is suspected, a transperineal biopsy reaches the front of the gland more easily than the standard transrectal route

## Related conditions

- [Benign prostatic hyperplasia](https://durgical.com/en/conditions/benign-prostatic-hyperplasia/)

## Test yourself

Think of the answer, then tap the question to see it.

## Why does primary cancer almost never start in the anterior fibromuscular stroma?

It is non-glandular: fibrous tissue and smooth muscle with almost no glands.

## Why are anterior prostate tumours near the anterior stroma often missed?

They are out of reach of the finger on rectal examination and outside a standard posterior-weighted biopsy; MRI and targeted biopsy find them.

## Which venous structure lies directly in front of the anterior fibromuscular stroma?

The dorsal vein complex, controlled early in radical prostatectomy to limit bleeding.

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Educational information, not medical advice. For any symptom, see a health professional.

## Its names

**Official Latin (TA2)**
isthmus prostatae

**Official Spanish (DeCS)**
Istmo de la próstata

**English (TA2)**
Isthmus of prostate

## Related

- [Prostate](https://durgical.com/en/anatomy/prostate/)
- [External urethral sphincter](https://durgical.com/en/anatomy/female-external-urethral-sphincter/)

Sources: [Anatomy, Abdomen and Pelvis, Prostate](https://www.ncbi.nlm.nih.gov/books/NBK540987/).

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Representative model, for educational purposes only.

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Source: https://durgical.com/en/anatomy/isthmus-of-prostate/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/anatomy/isthmus-of-prostate/