Acute pelvic pain

Acute pelvic pain in females is a common presentation. Whilst it often seems to drive terror into the hearts of clinicians patients are often a lot more straightforward to assess that you think they will be.  In fact, the whole of non-specialist gynae is a topic that lends itself well to Bayesian decision modelling. Your patient is either “pregnant” or “not pregnant” and that she might have pain, bleeding, discharge or a combination of these things. Today I want to focus on acute pelvic pain as the primary presenting symptom.

Alina is 15. She presents to A&E in significant pain and is tearful.  She describes a 2-3 day history of intermittent lower abdominal pain which doesn’t appear to localize to any particular side but which is possibly slightly worse on the left. She’s been having 1g paracetamol four times a day for the last 48 hours as well as maximum doses of ibuprofen. They seem to dent the pain a bit but when they wear off she is left crying with pain and unable to cope. She describes it as “like the worst period pain I’ve ever had” but is adamant it isn’t her period as “that was 2 weeks ago”. It is a lot worse today and she has been vomiting with the pain.  Alina is struggling to stand as she sobs her way through triage leaning on her mum.

At this point it is probably worth having a list of possible differential diagnoses in your head to help to tailor your assessment to come to a diagnosis and most importantly to rule out the life threatening “never miss” causes of severe pelvic pain. 

Possible diffentials for acute pelvic pain in the adolescent:

• Ectopic pregnancy
• Pelvic Inflammatory Disease
• Miscarriage
• Dysmenorrhoea
• Ruptured or torted ovarian cyst
• Torted ovary
• Mittelschmerz
• Endometriosis
• Appendicitis
• UTI
• Sickle cell crisis
• Porphyria
• Haematocolpos
• Unexplained

Ectopic pregnancy

Top of your list of things to look for and rule out in a case of acute pelvic pain in a female of childbearing age has got to be ectopic pregnancy.  A negative urine pregnancy test, especially in the context of a young person with a reliable menstrual history AND with a LARC method of contraception on board AND/OR a sexual history of not being sexually active is a good way to rule out pregnancy rapidly.  In this presentation there would be little, if any, justification for not doing a urinary pregnancy test. In many A&E departments a pregnancy test is a standard triage investigation along with a urine dip for blood/protein/WBC and nitrite before a clinician even starts their assessment. If the pregnancy test is positive, she needs a comprehensive assessment to exclude other causes of acute pain. But until an ectopic has been fully excluded, it must remain the working diagnosis of the moment with anything else coming second. 

The NICE guidelines from 2019 provide an extremely useful and user-friendly guide to managing ectopic/early miscarriage.  NICE remind us that PV bleeding and pain, whilst common symptoms of an ectopic, are not always present.  In order not to miss it we need to have a low threshold for doing a urinary pregnancy test in any female of reproductive age. This table from the guidelines is a helpful summary of other less common presenting symptoms in which a pregnancy test may well be indicated.

Advice around examining patients with a suspected ectopic pregnancy seem to vary from department to department and, interestingly, NICE make no comment on this. In primary care, the traditional teaching is not to do a bimanual examination in case the pressure of the physical examination on the adnexal mass ruptures the ectopic. In a hospital setting, with resus and surgical facilities, a bimanual looking for cervical excitation and guarding may help make the diagnosis.  If they are stable an expectant approach looking for B-hCG doubling (for a normal pregnancy) or falling (for a failed pregnancy) may be adopted. If medical management with methotrexate is chosen a baseline B-hCG is vital.

A patient with a probable ectopic needs to have bloods taken for FBC, crossmatch and B-hCG and should be referred on the on call gynae service promptly.

Alina’s pregnancy test is negative and she shows you the Nexplanon contraceptive implant she has in her left arm. You start to relax. An ectopic pregnancy is highly unlikely and this almost certainly isn’t a threatened miscarriage.

Pelvic inflammatory disease

Next one down in the serious/scary things to rule in or out urgently is Pelvic Inflammatory Disease.  The British Association for the Study of Sexual Health (BASSH) recommend that acute pelvic pain in a non-pregnant woman aged <25 is PID until proven otherwise.  1 in 60 primary care consultations in women aged under 45 is for PID.  Youth is a major risk factor especially if associated with multiple or new sexual partners.  Taking a sensitive but full sexual history is vital. Asking direct questions such as “when was the last time you had sex?”, “who was it with?”, “did you use a condom?”, “how many other people have you had sex with in the last 3 months?” are likely to yield clearer answers. 

In teenagers try and avoid the phrase “are you sexually active?”. Most won’t understand the nuance of the question and the number of teenagers who answer “no” but later turn out to be “sexually active” is high.  You may well need to ask these questions more than once, ideally without the parent present. Acknowledging that they are having sex, especially with multiple partners, may well not be anything they want their parent to know.  In the UK and the USA the incidence of chlamydia, in the 14-24 age group, is quoted as 1 in 20 women.

The Commonest pathogens in PID are chlamydia (4-35%), gonorrhoea (2-3%), mycoplasma genitalium.  Pathogen negative PID is not uncommon (but is a diagnosis of exclusion).  BASSH advice is that “A diagnosis of PID should be considered, and usually empirical antibiotic treatment offered, in any sexually active woman who has recent onset, lower abdominal pain associated with local tenderness on bimanual vaginal examination, in whom pregnancy has been excluded and no other cause for the pain has been identified”

Any patient with suspected PID needs cervical and HVS “triple swabs” taking for chlamydia, gonorrhoea, trichomonas and M. genitalium.  The treatment of choice in PID is IM ceftriaxone 1g stat.  If M. genitalium is found the treatment is moxifloxacin 400mg daily for 14 days.  M genitalium is difficult to isolate and culture and is best seen on NAAT swabs done urgently.  All patients with PID need to be referred to the local GUM clinic for ongoing treatment and contact tracing.  Complications of PID include sepsis, pelvic abscess, chronic pain, infertility as well as ectopic pregnancy so it is really important to suspect, identify and treat to prevent disability or serious illness.

When to admit in PID:

• Pyrexia >38⁰C.
• Signs of tubo-ovarian abscess (e.g. fluctuant mass in adnexa).
• Signs of pelvic peritonitis (rebound, guarding, cervical motion tenderness).
• No response to oral treatment.
• Pregnancy

Endometriosis

This is an easily missed diagnosis and a common cause of pelvic pain. Ectopic deposits of endometrial tissue appear in locations outside the uterine cavity, typically on the ovaries, fallopian tubes, and in the peritoneum.  These deposits respond to hormonal changes during the menstrual cycle and during menstruation they bleed, causing irritation and pain. The pain, classically, is cyclical, and at its worst in the day or two before menstruation. As the condition progresses and becomes more chronic adhesions can form and the pain can become more severe and constant.  It is worth being aware that laparoscopy findings do not always correlate well with symptoms. Some women can have severe symptoms with what appears visually to be small/minimal deposits and other woman can have minimal symptoms with quite “severe disease”.  On average it can take 6 years from first presentation to make a diagnosis.  Management is usually symptomatic with the combined contraceptive pill, analgesia and sometimes surgery.

Haematocolpos

This is a really rare condition that is worth bearing in mind even though it may well be a once in a career diagnosis presentation. Menstrual blood builds up in the vagina and uterus due to presence of a thick complete vaginal membrane – an “imperforate hymen”. Classically the adolescent presents with cyclical pelvic pain and primary amenorrhoea.  An ultrasound will show a grossly distended uterus filled with old blood and treatment involves surgical division of the vaginal membrane under a general anaesthetic.

Mittelschmerz

Translated literally from the German as “middle pain”, Mittelschmerz is cyclical pain occurring mid-cycle at the point of ovulation. It is uncommon. It will not occur in someone on an anovulant contraception, and whilst painful, is unlikely to render someone unwell enough to present to ED.

Alina’s abdominal examination reveals tenderness globally over the lower abdomen but worst in the left iliac fossa with some guarding.  She tells you she has not had sex for 3-4 months and has no PV bleeding or discharge.  You attempt a bimanual and speculum examination with verbal consent and the support of her mum and a nurse, but she is crying in severe pain and you have to stop. She is tachycardic with a HR of 122 but her other observations are normal. Her FBC, CRP and urine dip are normal as was the urinary pregnancy test. 

You suspect ovarian pathology, either a ruptured or torted cyst or an ovarian torsion and arrange an ultrasound scan.

Ovarian cyst

Ovarian cysts occur in around 10% of pre-menopausal women and are often an incidental finding on an ultrasound scan done for an unconnected reason. The vast majority are benign in nature, asymptomatic and require no treatment.  The RCOG Green Top guideline 63 from 2011 advises that the majority of asymptomatic incidental cysts should be managed conservatively reassuring us that “the overall incidence of a symptomatic ovarian cyst in a premenopausal female being malignant is approximately 1:1000”. Most of us remember the ovarian teratoma from our embryology and pathology lectures as undergraduates. Ovarian teratomas are almost always benign, though scary looking if well differentiated, and containing teeth or hair. This is in contrast to testicular teratomas which have a high risk of malignancy.

An ovarian cyst can rupture or can twist on its pedicle – leading to torsion of an ovarian cyst. Both can result in acute pelvic pain associated with peritonism and vomiting.  Diagnosis is usually be made on ultrasound scan though occasional a diagnostic laparoscopy is the only way to identify the situation. Management of a ruptured or torted cyst will usually be surgical though a small ruptured cyst in a haemodynamically stable patient may be managed conservatively with observation.

Ovarian torsion

Ovarian torsion occurs when an ovary twists on its ligamentous supports compromising the blood supply and presenting as acute pain. This is often associated with peritonism and vomiting. A rapid diagnosis is important in to save the ovary and conserve future fertility.  The twisted pedicle may be visualized on ultrasound scanning or may only be seen on diagnostic laparoscopy.  Treatment is always surgical and the ovary may not always be salvageable.

An urgent ultrasound scan reveals an enlarged left ovary, dopplers with minimal venous flow but preservation of arterial flow, and a twisted vascular pedicle referred to as the whirlpool sign, there is free fluid in the Pouch of Douglas. Alina is consented for a laparoscopy to include attempt to untwist and fix the ovary but with consent to perform oophorectomy if this is unsuccessful.  Unfortunately the surgeon is unable to save the ovary and an oophorectomy is required. Alina makes a good recovery and is discharged home 36 hours post operatively.

Selected references

NICE NG126 April 2019 – Ectopic Pregnancy and Miscarriage, initial presentation and management 

RCOG Green Top Guidelines on ectopic pregnancy 2016 

BASSH 2019 guideline update on PID 

https://www.aafp.org/afp/2010/0715/p141.html