Sepsis in the peripartum and postpartum period

Sepsis in the pregnant/delivering/delivered patient is a kettle of very different fish, and requires some distinct considerations, blending some of the unique issues from other topics. Question 20 from the second paper of 2023 dealt with postpartum sepsis, otherwise referred to as "puerperal" sepsis, from Latin (where puer  is "child" and parus is "bearing", hence para the childbearing woman). Puerperal sepsis is whatever infection you get in your genital tract between the rupture of membranes up until 42 days postpartum, the timeframe being apparently defined largely arbitrarily. The WHO would anyway prefer for you to use the term “maternal peripartum infections” because that shifts the focus off the genitals. Characteristic puerperal organisms and generic sepsis management aside, the examiners referred to "other sepsis-specific management considerations" in the SAQ, attributing 40% of the marks to this matter, which means it deserves some extra attention.

Differential diagnosis for puerperal sepsis

The postpartum patient can be shocked and in multiorgan system failure for a number of possible reasons, not limited to:

  • Amniotic fluid embolism
  • PE
  • Sepsis
  • Cardiomyopathy of pregnancy
  • HELLP
  • Haemorrhage

If you add "fever" to this, you narrow the range somewhat. Sources of sepsis in the parturient include:

  • Everything below the belt (most common causes)
    • Endometritis
    • Chorioamnionitis
    • Urinary tract
  • Extragenital infections that either occur as the result of pregnancy, or are exacerbated by it:
    • Cholecystitis
    • Mastitis
  • Complications of delivery and general hospital stay:
    • Bowel injury during caesarian
    • Perineal infections
    • Line sepsis from PIVCs
    • Urosepsis from IDCs
    • Caesarian wound infection
  • Incidental sepsis of completely unrelated source, eg. pneumonia
  • Any of the above, but with toxic shock syndrome
  • Nonifectious causes of fever, eg. PE or drug withdrawal

According to Jain et al (2021), about 30% never have a source identified.

Common organisms in puerperal sepsis

The following organisms are listed in the excellent work by Knowles et al (2015):

  • Gram positive aerobes:
    • Staphylococcus aureus
  • Gram negative aerobes:
    • Klebsiella
    • Proteus
    • Enterobacter
    • Enterococcus
    • Escherichia coli.
  • Anaerobes:
    • Peptostreptococcus
    • Peptococcus
    • Bacteroides
    • Fusobacterium
    • Prevotella
    • Clostridium

And often several of these all at once, rather than any sole organism. Polymicrobial sepsis is more common in these people. According to the 2017 SOMANZ guidelines for sepsis in pregnancy, the most important four are:

  • Group A streptococci, eg. S.pyogenes (because they are the most common cause of maternal death)
  • E.Coli is the most common cause of peripartum sepsis overall
  • Group B streptococci eg. S.agalactiae (as 25% of Australian women are colonised, and is the next most important cause)
  • S.aureus, as this is the most likely cause of mastitis

Initial empirical antibiotics for puerperal sepsis

For chorioamnionitis, the SOMANZ guidelines recommend broad spectrum antibiotics covering a range of organisms. The rationale for this breadth is that there is a number of possible simultaneously important organisms. Thus:

  • SOMANZ recommend ampicillin + gentamicin + metronidazole
  • eTG recommend ampicillin + gentamicin, and to add metraonidazole only if the patient is unable to have ampicillin

Plus add clindamycin if Grpup B strep is identified or the patient is severely shocked (rationale is that if the patient has toxic shock syndrome, the clindamycin should help block the pathways of toxin synthesis)

Source control in puerperal sepsis

Provided you know what the source is, you should probably make some effort to control it. Indeed CICM examiners made this aspect occupy two of the possible four marks for part (c) of Question 20 from the second paper of 2023. This probably reflects the importance of the source control as a lifesaving activity rather than the knowledge content of the answer, which would have been limited (for example the college marking criteria guide mentions such generic things as "laparotomy and washout", "hysterectomy" and "D&C". These generic source control options in order of increasing morbidity are as follows:

  • Removal/replacement of any potentially infected IV devices and IDC
  • Delivery. If the child remains in situ.
  • Incision and drainage of any superfical abscess or collection
  • D&C, an examination under anaesthetic, to remove retained products, or debride necrotic tissue
  • Laparoscopic washout of pyoperitoneum
  • Laparotomy and washout, as needed
  • Hysterectomy, reserved for disastrous situations

Unique elements of puerperal sepsis

What's so special about the female genitourinary tract and the prevailing host conditions at the end of pregnancy? Well, as mentioned above, the host is vulnerable but young and with solid compensatory mechanisms. Jain et al (2021) have this excellent list of special features, paraphrased below

  • Predisposition to infection

    • Pregnancy makes you susceptible to infection immunologically

    • Delivery makes you susceptible to sepsis mechanically, by opening the barrier between the "internal milieu" and the organisms of the exterior

    • Delivery also puts you at risk of having invasive procedures, not limited to the vagina (eg. cannulas, IDCs, etc)

    • The genitorurinary tract during this time is highly vascular which means pathogens have rapid access to the circulation

  • Factors that increase the severity of sepsis in the parturient

    • The organism is often one of considerable virulence, eg. Group A strep (i.e. toxic shock syndrome is on the menu)

    • The infections are most often polymicrobial, so standard surgical prophylaxis may not cover them

  • Difficulty making the diagnosis:

    • During delivery, there is always tachycardia  and tachypnoea, and inflammatory markers will be already elevated

    • The patient is usually young and physiologically robust, which means they will compensate considerably
    • The patient is immunocompromised by the effects of pregnancy, which means they may not mount much of a fever
    • Many other complications of delivery (eg. haemorrhage) are more common and may be considered first, delaying the diagnosis of sepsis, or may in fact be concurrent with sepsis
  • Added logistical issues
    • There are potentially two patients, one of which is much less robust, and which will require a whole separate team to deal with them
    • The choice of medications for the management of sepsis is limited by lactation and by whether the foetus remains in situ

So, what does this add to the management of sepsis, as asked by the college in the last four marks of Question 20 from the second paper of 2023?

  • Clindamycin, as toxic shock syndrome is a likely differential
  • IV immunoglobulin, for the same reason, and also to cover necrotising fasciitis, not to mention the possibility that the pregnant patient may be hypogammaglobulinaemic
  • Notification: S.pyogenes is a notifiable disease in Australia
  •  

References

Yadav, Garima. "Puerperal Sepsis and Septic Shock." Infections and Pregnancy. Singapore: Springer Singapore, 2022. 509-522.

Vaught, Arthur J. "Peripartum Sepsis." Current Obstetrics and Gynecology Reports 12.4 (2023): 209-214.

Jain, Vanita, Aashima Arora, and Kajal Jain. "Sepsis in the Parturient." Indian Journal of Critical Care Medicine: Peer-reviewed, Official Publication of Indian Society of Critical Care Medicine 25.Suppl 3 (2021): S267.

Knowles, S. J., et al. "Maternal sepsis incidence, aetiology and outcome for mother and fetus: a prospective study.BJOG: An International Journal of Obstetrics & Gynaecology 122.5 (2015): 663-671.

Bowyer, Lucy, et al. "SOMANZ guidelines for the investigation and management sepsis in pregnancy." Australian and New Zealand Journal of Obstetrics and Gynaecology 57.5 (2017): 540-551.