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[Lymphatic system](https://durgical.com/en/anatomy/system/lymphatic-system/) · [Pelvis](https://durgical.com/en/anatomy/region/pelvis/)

# Obturator nodes

The obturator nodes are lymph nodes on the pelvic side wall; they filter lymph from the [cervix](https://durgical.com/en/anatomy/cervix-of-uterus/), uterus and bladder and are checked when such cancers are staged.

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## What it is

Lymph nodes on the side wall of the [pelvis](https://durgical.com/en/anatomy/region/pelvis/), next to the obturator nerve.

## What it does

Filter lymph from the cervix, uterus and bladder; among the first checked when a gynaecological cancer is staged.

## Key points

- One of the most common sentinel node sites in early cervical cancer, together with the external iliac and interiliac nodes
- They lie in the obturator fossa, below the external iliac vein and against the side wall, with the obturator nerve running through the same fat
- Also an early site of spread for [prostate](https://durgical.com/en/anatomy/prostate/) and bladder cancer, so they are removed in pelvic lymph node dissection for those cancers

## Key facts

**Where**
Lateral pelvic wall along the obturator nerve and vessels, below the external iliac vein

**Drains**
Cervix, uterine body, upper [vagina](https://durgical.com/en/anatomy/vagina/), bladder

**Into**
External and [common iliac nodes](https://durgical.com/en/anatomy/common-iliac-nodes/)

## Relations

**Above**
[External iliac vein](https://durgical.com/en/anatomy/external-iliac-vein/)

**Lateral**
[Obturator internus](https://durgical.com/en/anatomy/obturator-internus/) and the pelvic side wall

**Medial**
[Urinary bladder](https://durgical.com/en/anatomy/urinary-bladder/) and the medial umbilical ligament (obliterated umbilical artery)

**Below**
[Obturator nerve](https://durgical.com/en/anatomy/obturator-nerve/), artery and vein on their way to the obturator canal

## How to find it

In surgery they are reached by lifting the external iliac vein and drawing the bladder medially; the obturator nerve is identified in the fat before the nodes are removed.

## On imaging

On CT, MRI or PET-CT they lie in the fat of the obturator fossa below the external iliac vein, against the pelvic side wall. A short- [axis](https://durgical.com/en/anatomy/axis/) diameter over 10 mm, a round shape, irregular margins or central necrosis suggest metastasis, and PET-CT adds uptake. Normal-sized nodes can still hold tumour, which is why sentinel node mapping is used in early cervical cancer.

## Clinical notes

- Obturator nerve injury during dissection weakens hip adduction and numbs the inner thigh
- Sentinel node mapping injects a dye, a radiotracer or a fluorescent agent into the cervix and follows it to the first pelvic node, often in this group
- A corona mortis (a vascular link between the obturator and external iliac or inferior [epigastric vessels](https://durgical.com/en/anatomy/inferior-epigastric-artery/) behind the pubis) can bleed during dissection

## Anatomical variants

- Classifications differ: some texts count them as part of the external iliac chain, others with the internal iliac nodes

## Related conditions

- [Cervical cancer](https://durgical.com/en/conditions/cervical-cancer/)
- [Ovarian cancer](https://durgical.com/en/conditions/ovarian-cancer/)
- [Endometrial cancer](https://durgical.com/en/conditions/endometrial-cancer/)
- [Bladder cancer](https://durgical.com/en/conditions/bladder-cancer/)

## Test yourself

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

## Where do the obturator nodes lie, and which nerve runs through the same fat?

In the obturator fossa below the external iliac vein against the side wall; the obturator nerve.

## Which cancers spread early to the obturator nodes?

Cervical cancer (a common sentinel node site), and prostate and bladder cancer.

## What deficit follows obturator nerve injury during obturator node dissection?

Weak hip adduction and numbness of the inner thigh.

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

## Its names

**Official Latin (TA2)**
nodi obturatorii TA2 5333

**Official Spanish (DeCS)**
Nódulos linfáticos obturadores DeCS D008198

**English (TA2)**
Obturator nodes

Sources: Terminologia Anatomica (TA2); [DeCS](https://decs.bvsalud.org/es/ths/resource/?id=8375); [Anatomy, Abdomen and Pelvis: Female Pelvic Cavity](https://www.ncbi.nlm.nih.gov/books/NBK538435/); [Anatomy, Abdomen and Pelvis: Lymphatic Drainage](https://www.ncbi.nlm.nih.gov/books/NBK557720/).

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Representative model, for educational purposes only.

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